I don’t know any gardeners who casually grow dahlias. Their fireworks riot of color has an intoxicating effect. You may start with one dahlia, but before you know it you have torn out the roses, planted five hundred tubers and (in at least one documented case), transformed an old tennis court into a fenced garden to make room for more flowers.
But dahlia devotees pay a price. In cold climates (read: the ground freezes), dahlia tubers need to come out of the garden if they are to survive the winter. Dig them up and store them in the basement, garage, or a protected shed—and dahlias will reward you next summer with more enormous puffball blooms. It’s worth the effort.
Here are step-by-step instructions for how to store dahlia tubers in winter:
Photography by Mimi Giboin for Gardenista.
1. Wait for the first frost.
Above: Dahlias will bloom well into autumn if you deadhead them to coax more flowers. But frost will put a stop to that.
Flowers will wilt, leaves will blacken, and dahlia stems will die back after the first frost; you’ll know it’s time to store tubers in a safe spot for the winter.
2. Dig up dahlias.
Above: Be careful when you dig up dahlias because, as you can see, a single plant may have a clump of connected tubers and a far-reaching root system.
To dig up, first cut back stalks to a height of 2 to 3 inches. Then start about a foot away from the plant, loosening soil all around the roots and digging deep enough (18 to 24 inches) to get your shovel underneath the dahlia to tease it out of the ground.
Dig up one clump of tubers at a time and be gentle; the tubers are fragile and break apart easily.
3. Rinse off dirt.
Above: Use a gentle spray from a garden hose to wash off soil so you can see the tubers and root system of individual clumps of dahlias.
I learned that one simple gardening trick can boost harvests quickly while cutting pest numbers almost in half. The trick is companion planting: nature’s way of helping plants work better together.
After many seasons of trial and error, this method turned my weak veggie beds into a healthy, busy garden in no time.
No need to stress about fancy layouts. These 10 plant partners work well with little effort. Ready to match plants the easy way? Let’s go.
Plant Partners That Work Wonders
1. Tomatoes & Basil: A Reliable Match
This pair isn’t just delicious on the plate. Basil’s strong smell helps keep away pests like aphids and hornworms that usually bother tomatoes.
Growing them together can even make tomatoes taste better. (Seriously. My tomatoes tasted so much better once I planted basil beside them.)
2. Carrots & Onions: A Simple Defense
Carrot flies can wipe out a crop fast, but onions help block them. In return, carrots help loosen the soil for onion bulbs. They just work well together.
3. Corn & Beans: The Old “Three Sisters” Duo
This old planting method makes sense. Beans add nitrogen to the soil, which corn needs. The corn stalks give the beans something to climb. It’s a natural setup that works smoothly.
4. Cucumbers & Nasturtiums: The Decoy
Nasturtiums act like bait, pulling pests like aphids and beetles away from cucumbers. They also have pretty flowers that you can eat with a pepper-like taste.
5. Peppers & Marigolds: Root Protectors
A common mistake is planting peppers without help. Marigold roots release compounds that chase away nematodes that damage pepper roots.
Some studies show that marigolds can reduce nematode populations by up to 90%. Their blooms look nice, too.
6. Lettuce & Radishes: Soil Helpers
Radishes break up compacted soil, allowing lettuce roots to grow deeper. This makes lettuce stronger on hot and dry days. Radishes also grow fast, so you get an early harvest while waiting for your lettuce.
7. Squash & Borage: Bee Magnets
Squash needs more bees, and borage attracts them. These bright blue flowers pull in loads of pollinators and help keep pests away from squash. Knowing this pairing gives you better fruit.
8. Potatoes & Horseradish: A Surprise Team
This pair sounds odd, but it works. Horseradish contains natural compounds that help keep potatoes strong and beetles away. Plant horseradish at the corners of the potato bed for protection.
9. Strawberries & Thyme: Berry Guards
Slugs love strawberries, but thyme helps stop them with its strong scent. Thyme also acts as ground cover, keeping berries off the soil and reducing fungal problems. Simple and smart.
10. Cabbage & Dill: Friendly Bug Attractors
Dill doesn’t chase pests. Instead, it brings in helpful insects like ladybugs and lacewings that eat cabbage worms. It’s like having tiny guards watching over your cabbages.
Why Companion Planting Works
Companion planting is more than old advice. It’s backed by how plants interact. They use scents and root signals to communicate with one another. The results can be big:
Less pest damage, fewer sprays
Better pollination
Grow more in small spaces
Better soil use
Shade where needed
When you match plants well, everything grows better together.
How To Start
Try just two or three partner groups this season. Watch how plant health, pest problems, and harvest amounts change.
Remember: it’s not just about putting plants next to each other. It’s about letting them support each other. Keep them close but not crowded; about 12–18 inches apart works for most pairs.
With the right partners, your garden becomes a group that works together instead of single plants growing alone. That’s the goal for most of us anyway.
A dahlia tuber is the below-ground portion of the plant.
It’s a starchy storage organ that holds the food, nutrients, and water needed for growth as the plant establishes feeder roots.
They come in a variety of shapes. Some look distinctly yam-like, others can be long and thin, plump and rounded, or elongated teardrops, depending on the variety.
Photo by Lorna Kring.
For the purposes of storage and division, there are three sections to be aware of:
The fleshy crown located at the base of the stem.
The thin neck that attaches the tuber to the crown.
The large tuber that’s attached to the crown by the neck.
The crown is only the only part of the plant that develops growth eyes.
For this reason, don’t try to propagate new plants using tubers that have grown from others – without a piece of crown, new plants won’t develop.
Also, should you inadvertently break off actively growing eyes, it’s not a problem. New ones will push up from the crown at the same location.
Dig and Lift
When first lifted, dahlia tubers can have fragile necks.
If possible, dig them out in the morning and allow them to sit on the ground for a few hours before cleaning and dividing – the necks will be less brittle and easier to handle.
To remove a clump, cut down stems to approximately 12 inches from the ground, if you haven’t done this in advance.
Mark a radius of approximately 12 inches around the clump and use a garden shovel or fork to dig down six to eight inches to loosen the soil.
When the soil is loose, insert your fork under the clump and lift it carefully. Grasp the flower stems to help you lift it if needed.
Gently knock off any large lumps of soil from the clump and rinse with a garden hose to remove any remaining dirt.
With a sharp, clean knife, cut away any pieces that are damaged, discolored, soft, or rotting.
Photo by Lorna Kring.
Invert the clump and set it upside down in a dry location for a few days. This allows any stem water to drain away and helps to remove excess moisture from the tubers.
This time spent drying, or curing, is important to prevent contamination from bacteria, fungus, mildew, and winter rot which can damage or destroy your tubers.
After the skin starts to wrinkle slightly, the tubers are dry enough for storage.
Winter Storage
Storing tubers is straightforward and a wide variety of containers can be used including cardboard or wooden boxes, paper bags, or styrofoam ice chests.
Your dahlia tubers should not be stored in plastic bins, containers, or bags as these tend to trap too much moisture which can easily lead to mildew and rot.
Photo by Lorna Kring.
They will require a dry to lightly moist packing medium. Coconut coir, peat moss, perlite, sand, sawdust, or vermiculite all work well for packing tubers.
For storage, line the box bottom with several layers of newsprint then add a generous layer of your chosen packing medium – two to three inches deep.
With clean, sharp garden shears, remove any long feeder roots growing from the tuber and any remaining pieces of stem.
Dust the tubers with a fungicide powder such as garden sulphur before storing, and ensure you apply it to any cut surfaces as well.
Place clumps of tubers inside the box on top of the packing medium ensuring that they’re not touching. Add more packing material on top until they are completely covered.
Close the box and store it in a cool, dark location such as a basement, cellar, garage, or shed.
To ensure viability, temperatures need to remain above freezing and below 50°F, with an ideal temperature range of 40 to 45°F.
Every month, inspect the tubers carefully and discard any that show signs of softness or rot.
In late winter or early spring, move your containers to a warm (60 to 70°F), dark location.
Every week, sprinkle a tablespoon of water on top of the packing medium until you are ready to plant them out.
The warmth and added moisture help the growth eyes to develop, which makes division easier.
Divide and Plant
After all risk of frost has passed, when you are ready to plant, remove the clumps from storage and gently shake off the storage medium.
Inspect the clump and discard any tubers that are moldy, soft, or rotten as well as those with broken or damaged necks.
“I don’t do frilly,” say Diane Schaub, director of gardens at Central Park Conservancy. We are standing under the shade of an old magnolia in the English garden, one of three smaller gardens within Central Park’s six-acre Conservatory Garden near the northeast corner of the park. Schaub, who earned a diploma from the New York Botanical Garden’s School of Professional Horticulture, has been curating the Conservatory Garden for more than 30 years. And while she does not do frilly, she does do color and texture, breathtakingly well. She has a painter’s eye for composition and an architect’s instinct for structural detail.
Below, we share her best color combinations for fall garden beds:
Above: “This is as frilly as I go,” she clarifies, indicating a velvet-leafed plant with burgundy leaves, beside the bluestone path. The plant in question is a Solenostemon (formerly classified as Coleus) and the cultivar is ‘Lancelot.’ Above: Solenostemon ‘Lancelot’ (paired with Salvia ‘Paul’) belongs to a crew of leafy annuals whose impact is felt dramatically in this garden, where the seasonal spectacle owes a great deal to plants whose interest lies in their foliage.
Purple + Yellow + Blue
Above: If you thought leaves were boring, think again. Solenostemon ‘Purple Prince’, black-leafed Dahlia ‘Mystic Illusion’, and Salvia farinacea ‘Victoria Blue.’
Above: A bed of Pennisetum setaceum ‘Rubrum’, Salvia x ‘Indigo Spires’, the leafy and lilac-striped Strobilanthes dyeranus, and elephant-eared Colocasia esculenta ‘Blue Hawaii’. The latter “makes the whole composition work,” says Schaub. Dark purple Pennisetum ‘Vertigo’ is in the background. Above: The English Garden is arranged in beds radiating from a central pond overhung by the largest crabapple tree in Central Park, leaves now turning yellow. Designed by Betty Sprout and opened in 1937, this part of the park was by the 1970s considered one of the most dangerous places in New York City. In 1980, the Central Park Conservancy was formed in response to the neglect the park had suffered in the previous two decades. Its founding director, Elizabeth Rogers, earmarked the Conservatory Gardens for renovation.
Growing up to 36 inches tall, the four-inch flowers are ideal as cut flowers and for creating colorful borders either alone or paired with yellows and pinks.
A mixture of ball flowers, the Summer Tango collection adds fiery heat to the garden with four-inch globes in glorious shades of burgundy, peachy orange, and purple while the mid-green foliage adds a cooler base.
Dahlias can be propagated by cuttings, tuber division, or seed. However, growing plants from seed is an unreliable method.
Most of the stock available for home gardens comes from hybrid cultivars, which may produce offspring untrue to the parents.
Cuttings
Cuttings are clones of the mother plant, so they always produce the same qualities.
Sprout cuttings can produce up to six new plants from a single tuber, but they require a controlled environment of consistent humidity, warm temperatures, and day length.
Dahlias are photosensitive, and to develop healthy feeder roots as well as tubers, they require a day length of 12 hours or greater. If needed, add a grow light to your setup to meet this rooting requirement.
In late winter or early spring, choose a selection of healthy, firm tubers from your storage bin.
Add four to six inches of moist potting soil to a tray – or create your own soil blend of one half aged compost and one half landscape sand.
Nestle tubers into the soil, covering the bottom two-thirds, but keeping the neck and crown above the soil.
Place the tray in a 65 to 75°F location where it can receive bright indirect light.
Keep the soil moist but not wet, and within three to four weeks, sprouts will emerge from the tubers.
Once the sprouts are three inches or taller, use a clean, sharp knife to carefully cut each sprout away, taking a small notch of tuber with it.
Remove the bottom set of leaves and dip the lower one to two inches of stem into a rooting compound, then gently shake off the excess.
Fill small, four- to six-inch pots with moist potting soil.
Make holes and insert three stems into each pot, one to two inches deep, and gently firm the soil around each stem.
Maintain even moisture in the potting medium, but do not allow it to become waterlogged.
Place in a 65 to 75°F location that receives bright, indirect light for at least 12 hours each day. Roots form in two to three weeks.
Eight to 10 weeks later, sprout cuttings can be transplanted to larger pots, or planted into the garden when soil temperatures warm to 55 to 60°F.
Dahlias are beloved by gardeners and florists for their large array of glorious colors and delightful flowers that range from miniature pompoms to giant dinnerplates!
Flowering from midsummer until the arrival of frost, they add fresh beauty to beds, borders, containers, and window boxes through the dog days of summer – just when other plants start to wear out from summer’s heat.
But with over 57,000 registered cultivars worldwide, choosing a selection for your garden can be a challenge.
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The American Dahlia Society (ADS) categorizes dahlias into three groups on the basis of color, form (or flower type), and size.
In our guide to growing dahlias, we cover how to cultivate these beauties. In this guide, we’ll take a look at the different classifications to help you choose the type that’s right for your garden.
Here’s what I’ll cover:
Dahlia Groups and Classification
Color
The ADS Color group lists 15 distinct shades or color combinations.
Bicolor
Bronze
Dark blend
Dark pink
Dark red
Flame
Lavender
Light blend
Orange
Pink
Purple and Black
Red
Variegated
White
Yellow
With every color available except true blue, you’re sure to find just the right shade for your garden palette.
Form
There are multiple flower types in the Form group, with different petal structures and bloom shapes.
1. Anemone
Anemone (AE) types are distinguished by at least one row of evenly spaced, flat ray petals surrounding a vivid, and often contrasting, pincushion center made of long, tubular florets.
They may also be bicolored, as in the case of ‘Polka Dot’ which features cream colored petals edged in dark pink surrounding a bright yellow center.
Blooms are four to six inches wide, and plants grow to a mature height of three to four feet.
Ball (BA) types are fully double flowers with a slightly flattened globe shape featuring furled, involute (incurved) petals in a gorgeous, spiral arrangement.
Petal tips can be blunt, flat, or indented.
Miniature Ball (MB) types have identical flower forms but in smaller sizes.
‘Cornel’ features deep red, cherry-colored, three- to four-inch blooms atop four-foot sturdy stems.
The globe-shaped flowers make a dramatic impact in the garden and in cut flower arrangements.
Cactus (C) types have long, pointed ray florets with petal edges that are involute (IC), revolute (edges rolled back), or straight (SC), radiating out from an open center in a somewhat spiky look.
‘Black Narcissus’ is a dramatic, moody semi-cactus cultivar with deep red petals that look almost black from a distance.
Adding texture, color, and interest to beds and borders, plants top out at two to three feet tall with large, six- to eight-inch blooms.
Collarette (CO) flowers have a flat, open face with a single outer row of regularly spaced ray florets, an inner collar of shorter petals (petaloids), and a fringed or tight center disk.
The inner collar and center disk are often contrasting.
‘Kelsey Anne Joy’ is a superb example of a Collarette dahlia, featuring apricot outer petals, with yellowish-reddish-gold inner petals surrounding a yellow center.
Two- to four-inch flowers bloom on stems that grow up to three feet tall.
Decorative cultivars are double petaled and open centered, with flat florets that may have a roll at the edges or tips.
Formal Decoratives (FD) have evenly spaced petals and a symmetrical flowerhead while informal Decoratives (ID) have twisted or wavy petals in a more irregular arrangement.
With five-inch flowers in blushed with soft pink, ‘Sweet Nathalie’ is an Formal Decorative type.
Laciniated (LC) types have uniformly arranged florets radiating from a disk or open center with involute or revolute edges.
A lengthwise split at the tips of the petals gives a fringed or “pinked” appearance like that of a carnation.
7. Mignon Single
Mignon Single (MS) is an open faced flower with a single row of uniform, slightly overlapping ray florets, in a flat plane surrounding a center disk that can be tightly furled or unfurled into a pincushion.
The delicate four-inch flowers are stunning when mass planted in beds and borders, and are available in a variety of colors. Compact plants top out at one- to two-feet tall.
You can find seeds for D. variabilis in a mixed packet of pinks, reds, yellows, and whites available at Eden Brothers.
8. Novelty, Open and Fully Double
Novelty flowers have characteristics that fall outside of the other classifications.
Novelty Open (NO) varieties have a disc center. Fully Double (NX) types have an open center surrounded by double petals.
9. Orchid
Orchid (O) types feature open flowers with a single row of uniform ray florets surrounding a tight disk center.
The florets are involute for at least two thirds of their length, giving a narrow, rolled effect.
Four-inch-wide flowers are light and stand erect atop three-foot stems.
10. Orchette
Orchette (OT) types are intricate blooms that combine the involute petal characteristics of the Orchid dahlia with an inner fringe of short petals (petaloids) surrounding a center disk typical of the Collarette form.
The petaloids may be flat or slightly curved towards the center of the bloom.
11. Peony
Peony (PE) types feature an open flower with two or more rows of flat or slightly cupped ray florets surrounding a center disk of open anthers on short filaments.
‘Bishop of Canterbury’ is a compact Peony type featuring deep magenta-pink petals that surround a dark golden center.
Flowers are five to six inches across on three-feet-tall sturdy stems.
Pompom (aka pompon) types (P) feature an open-centered, fully double flower in a rounded globe shape with rolled, involute florets that are blunt or round tipped.
Flowers are beautifully symmetrical with an appealing geometry.
‘Burlesca’ is a coral-pink cultivar with dainty four-inch flowers that look perfectly symmetrical.
Flower stalks can be up to three feet tall and may require staking.
Single (S), is an open faced flower with a single row of regular, overlapping ray florets in a flat plane surrounding a center disk.
The petals are flat or slightly cupped with blunt or pointed tips, and the center disk opens to reveal frilly anthers.
14. Stellar
Stellar (ST) types are fully double flowers with long and pointed cupped florets that recurve back towards the stem, giving the appearance of a shooting star.
Like the Ball types, there is no center disc.
15. Waterlily
Waterlily (WL) has fully double, symmetrical blooms with slightly cupped florets that open from a domed center to a saucer-shaped face.
Petals are broader and sparser than the Stellar types.
Size
The third group is Size, classified according to letter values.
Happy November! True, most tender annuals are done by now, and some tender perennials are showing signs of cold damage. But even if the more joyful aspects of gardening are past, there is still work to be done in the garden.
The chores for November fall into four categories, which handily all start with “p”: pruning (neatening up), protecting, propagating (and planting), and planning.
Above: To keep a red twig dogwood color vibrant, you need to either cut back the shrub to the ground every two to three years, or remove one quarter of a shrub’s stems every year. Photograph by Britt Willoughby Dyer, from Landscape Ideas: Blazing Color with Red Twig Dogwood, 5 Ways.
Once the leaves have dropped from your trees and shrubs and they’ve entered dormancy, it’s time to remove diseased or damaged branches (with trees, you should consider hiring an arborist) and evaluate their structures. That said, make sure the plant is not among those that shouldn’t be pruned until after they flower in spring. (See Your First Garden: What You Need to Know Before You Prune Shrubs and Trees.) Other plants that need to be cut back include certain berries (pruning out old canes will help the plant rejuvenate next year) and annual plants, which can be snipped down to the soil line, allowing the decaying roots to enrich the soil. But don’t get too hung up on neatness: Consider leaving perennials as they are, withered and brown, for overwintering insects and birds. And mulched leaves should be left in beds to return nutrients to the soil, hold moisture, and provide cover to beneficial insects. (For more on this topic, see Fall Gardening: 15 Ideas For What to Do With All Those Leaves.)
We don’t hate chrysanthemums. Let’s just get that out of the way. There is a lot to be said for their instant, impulse-buy autumnal cheer. A pot on the stoop (with a pumpkin or two), as the clock ticks towards Halloween, is welcoming. But muffin-top mums, rounded and mounded in a way that nature did not intend—left to their own devices, naturally-elegant perennial chrysanthemums are leggy and loose—have saturated the market. Their inescapable presence as October unspools makes it very easy to forget how many other flowers relish autumn.
The list of fall flowers is long, so here is a choice (albeit biased) collection.
Above: Fall flowers from Willow Wisp Organic Farm, at the Grand Army Plaza greenmarket in Brooklyn.
Celosia
Above: Celosia is a warm-weather annual whose flowers peak in fall.
In terms of commercial success, annual Celosia is beginning to nudge chrysanthemums off that front stoop. I see potfuls at my local deli in Brooklyn, at Whole Foods, at the market. Their rich, cockscomb colors are made for fall. These African annuals have taken off in the US. Aside from their tasseled ornamental appeal, the plants are in fact vegetables. They are eaten as cooked, leafy greens in their homeland and are reminiscent of amaranth greens, in flavor and texture.
Zinnias are a genus of annuals native to Mexico and Central America. They are one of the most rewarding cut flowers to enjoy as the weather cools. Available in a rainbow of colors (only blues are missing), more zinnia cultivars are being developed to withstand the mildew that sometimes bothers their leaves in humid climates. The blooms attract butterflies, hummingbirds, and bees.
Above: Dahlias at the Brooklyn Botanic Garden in October.
Dahlias might be the queens of autumn bouquets. Ranging from compactly petite pom-poms to ruffled flowers the size of side plates, with colors from candy stripes to rich jewel hues, the long-stalked flowers are cut-and-come-again for weeks from late summer through frost. Dahlias are hardy from USDA zones 8 to 10.
Tithonia
Above: Tithonia blooms from late summer till frost and is a boon to bees.
After it begins to flower in late summer, Mexican and Southwestern native annual Tithonia continues to blaze with color as nights dip into the 50s. The plant grows tall (upwards of five feet) and the blooms are very attractive to bees and other pollinators.
Marigold
Above: Annual marigolds (flor de muerto), play a key role in Día de los Muertos rituals in late October and early November.
The assertive scent of marigolds is a floral signal that the season has changed. Days are losing light, and the year’s end is approaching, staved off by celebrations that honor souls that have passed. Garlands of marigolds are a necessity for the Day of the Dead, and have a place at Halloween tables, too: The flowers are long-lasting in a vase, and marigold petals are edible. The plants have long been valued in companion planting traditions, and science bears this out: They secrete chemicals that deter nematodes and other pathogens.
I caught the dahlia bug many years ago, but haven’t won the lottery yet so, as much as I’d like to, I can’t fill my garden with piles of new tubers each spring.
So you’d better believe I threw a garden party when I mastered growing dahlias from seed.
For the price of one tuber, I can buy enough seeds to fill up my entire garden with dahlias, and even collect them from my existing plants!
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Our guide to growing dahlias has all you need to know to cultivate these beautiful flowers in your landscape.
If you want to breed dahlias to create new and unique specimens, growing from seed is a skill you must have.
When you take a cutting or divide a tuber, you’ll grow an exact genetic replica of the parent. But plants started from seed combine the characteristics of both parent plants.
You might end up with something magical and new that no one has seen before. Just imagine the accolades as you share your new dahlias with friends and fellow growers.
And it all started from a little seed. Are you dreaming of growing dahlias on the cheap or producing new types?
Here’s what we’ll go over in this guide so you can make that happen:
Dahlias grown from seed will develop tubers by the end of the summer.
But, before you can do that, we’ve got to plant those puppies.
When to Start
Dahlias are sensitive to cold temperatures and unless you live somewhere that never freezes, you’ll need to start the seeds indoors before putting them outside when it’s warm enough.
You should start the process of germination a month or two before the last predicted frost date in your area with the idea of planting out a month after the last predicted frost date.
If you are starting them in a cold basement or your other seedlings tend to take a long time to grow, give them two months. Otherwise, a month should be fine.
You can also direct sow into the garden if you live somewhere warm enough that dahlias can stay in the ground year-round.
This process is less reliable since you don’t have any control over the environmental conditions and herbivores like birds and voles seem to particularly love stealing them.
If you go this route, wait until the soil has warmed to 65°F before sowing.
Where to Buy Seeds
You won’t find seeds for some of the more elaborate dinnerplate dahlias or ball cultivars available, but there are many open-faced (single) or semi-double options out there.
These daisy-like dahlia flowers come in multiple bright colors including white, yellow, orange, red, and pink.
If you’re ready to harvest your own, keep reading.
Harvesting Seeds
As mentioned, dahlias started in this way won’t grow true, which means they won’t look exactly like the plant you collected the seeds from.
If you want an exact replica, you need to grow from tubers.
Dahlias are octoploids, which means they have four more sets of chromosomes than most flowering plants.
This provides incredible genetic diversity, but it also makes it extremely challenging to predict what plants grown from seed will look like.
You can try to cross two plants you love and hope the traits you desire will appear, but you can’t be sure. It’s a hit-and-miss process.
If you want to try crossing two plants, you will first need to cover your chosen receptive flowers in mesh or nylon bags to prevent natural pollination.
Then, when the dahlia flowers have fully opened and pollen has developed on the stamens, take the pollen from an open flower using a toothpick. Types with large, full heads make it a bit more difficult for you (and other) pollinators to find the pollen.
You might need to pluck some of the petals away from the center of the flower to find the pollen.
Rub this pollen on the stigmas of your chosen flowers. You’ll find the pods on the inside of the blossoms, but they aren’t ready until the blooms have aged and faded.
This happens in the fall for most types. Leave the blossoms on the plant until the first freeze is on the horizon.
Keep the blossoms covered in mesh bags to prevent birds from making off with your seeds.
To harvest the heads, cut the spent flower head away from the dahlia stem and gently rub the pods in your hand to release the seeds inside.
Some pods might be empty and some might have heaps. Set them on a towel or baking sheet to allow them to dry.
Once they feel totally dry, put the seeds in jars or envelopes and place them in a cool, dry area to store them until sowing time in the late winter or early spring.
Some may not be viable, but there’s no way to really know until you sow them and wait for them to germinate. I always sow more than I think I’ll need to compensate for any duds.
Sowing Seeds
To start, fill a tray with seed starting mix. You can also use potting soil, but don’t use one that contains fertilizer.
A seed starting mix is made without soil for a light, airy, water-retentive substrate that supports germination and growth without becoming oversaturated.
Arbico Organics carries an excellent product called Tank’s Pro-Lite Seeding & Potting Mix. It’s available in 16-quart bags.
Moisten the soil and then gently sprinkle the seeds on top. Place a thin layer of the medium over them and gently press down on the surface of the soil with your hands.
Set the containers on a heat mat set to maintain temperatures of 70 to 80°F and don’t panic if you don’t see any seedlings for a few weeks.
Dahlias aren’t in a hurry to pop up but that doesn’t mean they won’t.
Your setup should be near a window with bright, indirect light as the seedlings will require light as soon as they emerge. You don’t want any direct sunlight at first, though.
If you’d like to, you can cover the tray with plastic or glass to help the soil retain water. Whether you go this route or not, keep the soil moist but not wet – it should feel like a well-wrung-out sponge at all times.
As the seedlings emerge, you’ll eventually want to thin them out so they are about four to six inches apart. But, because the seeds tend to germinate sporadically, wait until the majority of the seeds have sprouted. I generally wait a month before thinning.
When the seedlings are about six inches tall and all risk of frost has passed, you can transplant them outdoors after a period of hardening off.
To harden them off, take the whole tray outside and set it in a sunny spot that’s protected from the wind for about an hour. Then bring it indoors. The next day, leave it outside for two hours. Keep adding an hour a day over the course of about a week.
After they are hardened off, transplant into the garden or into permanent containers. Dig holes six inches apart and make sure each hole is large enough to accommodate the roots.
Gently remove the seedlings from the tray, set them in the prepared holes, backfill with soil, and water in well.
If the resulting plant is one that you love, propagate it via tubers in the future so you can guarantee that it will be replicated faithfully.
Let’s Get This Party Started!
I have to confess that for me it isn’t all about saving money or developing new cultivars. I take a lot of pride in turning a little seed into a big, beautiful plant. It’s extremely fulfilling.
What’s your goal with growing dahlia seeds? Are you hoping to breed a few new styles and shapes? Or just looking to save a few bucks? Let us know in the comments section below.
I caught the dahlia bug many years ago, but haven’t won the lottery yet so, as much as I’d like to, I can’t fill my garden with piles of new tubers each spring.
So you’d better believe I threw a garden party when I mastered growing dahlias from seed.
For the price of one tuber, I can buy enough seeds to fill up my entire garden with dahlias, and even collect them from my existing plants!
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Our guide to growing dahlias has all you need to know to cultivate these beautiful flowers in your landscape.
If you want to breed dahlias to create new and unique specimens, growing from seed is a skill you must have.
When you take a cutting or divide a tuber, you’ll grow an exact genetic replica of the parent. But plants started from seed combine the characteristics of both parent plants.
You might end up with something magical and new that no one has seen before. Just imagine the accolades as you share your new dahlias with friends and fellow growers.
And it all started from a little seed. Are you dreaming of growing dahlias on the cheap or producing new types?
Here’s what we’ll go over in this guide so you can make that happen:
Dahlias grown from seed will develop tubers by the end of the summer.
But, before you can do that, we’ve got to plant those puppies.
When to Start
Dahlias are sensitive to cold temperatures and unless you live somewhere that never freezes, you’ll need to start the seeds indoors before putting them outside when it’s warm enough.
You should start the process of germination a month or two before the last predicted frost date in your area with the idea of planting out a month after the last predicted frost date.
If you are starting them in a cold basement or your other seedlings tend to take a long time to grow, give them two months. Otherwise, a month should be fine.
You can also direct sow into the garden if you live somewhere warm enough that dahlias can stay in the ground year-round.
This process is less reliable since you don’t have any control over the environmental conditions and herbivores like birds and voles seem to particularly love stealing them.
If you go this route, wait until the soil has warmed to 65°F before sowing.
Where to Buy Seeds
You won’t find seeds for some of the more elaborate dinnerplate dahlias or ball cultivars available, but there are many open-faced (single) or semi-double options out there.
These daisy-like dahlia flowers come in multiple bright colors including white, yellow, orange, red, and pink.
If you’re ready to harvest your own, keep reading.
Harvesting Seeds
As mentioned, dahlias started in this way won’t grow true, which means they won’t look exactly like the plant you collected the seeds from.
If you want an exact replica, you need to grow from tubers.
Dahlias are octoploids, which means they have four more sets of chromosomes than most flowering plants.
This provides incredible genetic diversity, but it also makes it extremely challenging to predict what plants grown from seed will look like.
You can try to cross two plants you love and hope the traits you desire will appear, but you can’t be sure. It’s a hit-and-miss process.
If you want to try crossing two plants, you will first need to cover your chosen receptive flowers in mesh or nylon bags to prevent natural pollination.
Then, when the dahlia flowers have fully opened and pollen has developed on the stamens, take the pollen from an open flower using a toothpick. Types with large, full heads make it a bit more difficult for you (and other) pollinators to find the pollen.
You might need to pluck some of the petals away from the center of the flower to find the pollen.
Rub this pollen on the stigmas of your chosen flowers. You’ll find the pods on the inside of the blossoms, but they aren’t ready until the blooms have aged and faded.
This happens in the fall for most types. Leave the blossoms on the plant until the first freeze is on the horizon.
Keep the blossoms covered in mesh bags to prevent birds from making off with your seeds.
To harvest the heads, cut the spent flower head away from the dahlia stem and gently rub the pods in your hand to release the seeds inside.
Some pods might be empty and some might have heaps. Set them on a towel or baking sheet to allow them to dry.
Once they feel totally dry, put the seeds in jars or envelopes and place them in a cool, dry area to store them until sowing time in the late winter or early spring.
Some may not be viable, but there’s no way to really know until you sow them and wait for them to germinate. I always sow more than I think I’ll need to compensate for any duds.
Sowing Seeds
To start, fill a tray with seed starting mix. You can also use potting soil, but don’t use one that contains fertilizer.
A seed starting mix is made without soil for a light, airy, water-retentive substrate that supports germination and growth without becoming oversaturated.
Arbico Organics carries an excellent product called Tank’s Pro-Lite Seeding & Potting Mix. It’s available in 16-quart bags.
Moisten the soil and then gently sprinkle the seeds on top. Place a thin layer of the medium over them and gently press down on the surface of the soil with your hands.
Set the containers on a heat mat set to maintain temperatures of 70 to 80°F and don’t panic if you don’t see any seedlings for a few weeks.
Dahlias aren’t in a hurry to pop up but that doesn’t mean they won’t.
Your setup should be near a window with bright, indirect light as the seedlings will require light as soon as they emerge. You don’t want any direct sunlight at first, though.
If you’d like to, you can cover the tray with plastic or glass to help the soil retain water. Whether you go this route or not, keep the soil moist but not wet – it should feel like a well-wrung-out sponge at all times.
As the seedlings emerge, you’ll eventually want to thin them out so they are about four to six inches apart. But, because the seeds tend to germinate sporadically, wait until the majority of the seeds have sprouted. I generally wait a month before thinning.
When the seedlings are about six inches tall and all risk of frost has passed, you can transplant them outdoors after a period of hardening off.
To harden them off, take the whole tray outside and set it in a sunny spot that’s protected from the wind for about an hour. Then bring it indoors. The next day, leave it outside for two hours. Keep adding an hour a day over the course of about a week.
After they are hardened off, transplant into the garden or into permanent containers. Dig holes six inches apart and make sure each hole is large enough to accommodate the roots.
Gently remove the seedlings from the tray, set them in the prepared holes, backfill with soil, and water in well.
If the resulting plant is one that you love, propagate it via tubers in the future so you can guarantee that it will be replicated faithfully.
Let’s Get This Party Started!
I have to confess that for me it isn’t all about saving money or developing new cultivars. I take a lot of pride in turning a little seed into a big, beautiful plant. It’s extremely fulfilling.
What’s your goal with growing dahlia seeds? Are you hoping to breed a few new styles and shapes? Or just looking to save a few bucks? Let us know in the comments section below.
When my ‘Labyrinth’ dahlia is in bloom, it’s truly one of my favorite flowers in the garden. How do you top giant, foot-wide flowers in an explosion of pink, salmon, orange, and cream?
I love them so much that I have replaced my plants not once, not twice, but three different times because of disease problems.
I love dahlias, but some diseases that affect them can be a real nuisance.
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Over the years, I’ve learned many techniques to avoid the problems that can plague these plants.
As is the case with many diseases, prevention is always best, and that’s especially true when it comes to dahlias.
Many of the common problems can spell the end of your dahlias. No do-overs, no cures, just digging out and tossing your once wonderful flowers.
A few diseases can be cured or otherwise dealt with, but prevention is the way to go.
In our guide to growing dahlias, we cover how to cultivate these beautiful blooms in your landscape. Healthy specimens are less likely to fall victim to infection from pathogens than those that are stressed or otherwise grown in suboptimal conditions.
In this guide, we’ll discuss nine of the most common diseases you’ll come across.
Here’s the list of the diseases we’re going to talk about:
1. Aster Yellows
Aster yellows is caused by a phytoplasma spread by leafhoppers.
When infected, the plants will have strange growth, such as witches’-brooms, distorted stems, and discoloration of the foliage and flowers.
Unfortunately, once your dahlia is infected, you can’t cure the disease. Since it can spread to other species in your garden, you’ll need to pull the affected dahlias and dispose of them.
To prevent the disease, you want to deny the pathogen the conditions it prefers. Do this by keeping plans well-spaced for proper airflow and don’t ever water from overhead. Only water at the soil level.
You should also be sure to sterilize your tools as you work in the garden. Never go from one plant to another without cleaning your pruners or other tools first.
You can use a 10 percent bleach solution (one part bleach mixed with nine parts water) which works just fine. I keep a little squirt bottle and some rags in my gardening toolbox so I have no excuse not to clean my tools.
If you know botrytis is a problem in your area, keep a close eye on your dahlias and the second you notice symptoms, start spraying your plants with fungicide.
Copper fungicide works well, but I swear by a product called Mycostop. I use it for all kinds of fungal problems that I encounter in the garden and it has never let me down.
It’s made with a bacterium derived from sphagnum peat moss.
Grab five or 25 grams at Arbico Organics and saturate the dahlias once every two weeks until the weather becomes drier and warmer, and symptoms have resolved.
You should also remove any symptomatic leaves and flowers.
3. Fusarium Wilt
Fusarium wilt is extremely similar to verticillium wilt, which we discuss below. These two diseases cause similar symptoms and they are both incurable.
The first sign, as the name suggests, is wilting in your plant, like you might see during periods of drought or underwatering. The soil might be sufficiently moist and you may be absolutely sure the dahlia has received the right amount of water, but it’s still wilting.
That’s because Fusarium oxysporum fungi have taken up residence in the xylem, or the part of the plant that transports water.
Beyond the aboveground symptoms of wilting, if you dig down, you’ll see a dark stem near the soil level and black roots and tubers. The leaves might turn yellow, as well.
The fungus thrives when it’s hot and temperatures are in the 80s and 90s. It can live in the soil, and on live or dead tissue.
Sadly, once it’s infected, you can’t save the dahlia. You’ll need to dig it up and dispose of all plant debris in the trash. Then, don’t grow anything in that soil that is susceptible to wilt.
You can spray your dahlias with Mycostop, which we talk about above, and it will stop the progression. But it won’t cure the disease, so this only works if you catch the problem early on.
4. Impatiens Necrotic Spot Virus
Impatiens necrotic spot (INSV) is caused by a virus that results in necrotic brown or black spots developing on the leaves.
It also causes sunken spots with yellow haloes, stunted growth, shoot and tip dieback, foliage yellowing, lack of flowering, and eventual plant death.
There is no cure for this disease and since it can spread to so many other species, you’ll need to pull and dispose of any symptomatic dahlias.
In the future, the only option is prevention, and that involves cleaning your tools as you work between plants, as we discussed above, and keeping western flower thrips (Frankliniella occidentalis) out of your garden.
Thrips carry and spread the virus, and once they start feeding on your dahlias, it might already be infected.
Our guide to thrips can help set you on the right path, but here’s a brief overview of how to repel them:
Row covers for low-growing species is ideal. Reflective mulch can help, too. Pheromone lures and sticky traps limit their numbers, and trap crops can draw them away from your more valuable garden specimens.
You should also invite or introduce predators like green lacewings, minute pirate bugs, and parasitic wasps into your garden.
You can purchase green lacewing eggs or larvae in quantities from 1,000 to 250,000 at Arbico Organics.
5. Mosaic Virus
Dahlia mosaic virus is a pathogen in the Caulimovirus genus, with the binomial C. dahliae, that has multiple strains, including DMV-D10, DMV-Holland, DMV-Portland, dahlia common mosaic virus (DCMV).
It can be hard to identify the symptoms because they can be vague or even nonexistent. Your dahlias might seem just sort of sickly, with stunted growth or less-than-impressive flowering. Some plants might not bloom at all.
You may also see yellow or cream mosaic patterns on the leaves, or chlorosis. The veins might lack color as well. Flowers might be discolored or exhibit strange patches of discoloration.
Distorted growth can occur on all parts of the plant, or the leaves or stems might have necrotic lesions.
You might need to send a sample of your plant to your local extension or University diagnostic lab to be certain that it’s infected with mosaic virus. If it proves to be, you’ll need to dig up the dahlia and dispose of it, along with any fallen debris.
On dahlias, powdery mildew is usually more in the ugly but not deadly category.
Powdery mildew is caused by the fungi Erysiphe cichoracearum and E. polygoni, which are obligate parasites. What does that mean? It means they can’t survive without a host, the pathogens need a live plant to survive and reproduce.
That’s good news for us because it means the pathogens don’t want to kill their host and they can’t hang out in the soil even after your plant is dug up and overwintered out of the garden.
The spores need some humidity, around 60 percent, but not tons of water, and temperatures between 59 to 82°F to germinate. Then, the spores wait for a nice dry day with a breeze or hitch a ride on aphids to spread around the garden to infect all your dahlias.
Once present, you’ll notice a powdery coating on the leaves and maybe some distortion of the foliage if the disease has advanced.
Prune off any symptomatic leaves, unless more than 50 percent of the plant is infected. If it is, go straight to fungicides. A low level infection might be remedied through pruning and treating with milk.
Yes, the stuff in your refrigerator.
A mixture of one part milk and nine parts water will usually be enough to stop or eliminate the disease, though you can increase the mixture until it’s 50:50 for heavier infections.
For heavily infected dahlias that need fungicides, treat them with one or two alternating products to get rid of it.
Bacterial stem rot is a gross disease. It’s caused by the bacteria Pectobacterium carotovora subsp. carotovora (previously Erwinia cartovora) and when the pathogen attacks your plants, the lower parts of the stems will turn black and mushy on the interior.
They also give off a distinct, foul odor.
If you walk past your plants and catch a whiff of something extremely unpleasant, crouch down and look at the base of the stem. Give it a gentle squeeze, and if it feels soft, your dahlia is likely suffering from stem rot.
The causal pathogen needs water to survive, and it can’t live long without a host. But it travels easily on tools, shoes, plants, or it can hitch a ride on insects.
There’s no cure, and it will spread to a huge range of other species, from potatoes to celery.
If your dahlias are infected, you’ll need to rip them out and dispose of them. You should also leave the area fallow until the following year to avoid infecting another plant.
In the future, be super careful about garden hygiene and do your best to keep pests out of the garden.
8. Tomato Spotted Wilt Virus
Tomato spotted wilt (TSWV) is extremely similar to impatiens necrotic spot. For a while, they were thought to be the same virus, but genetic research has shown them to be separate species.
In addition to the shoot and tip dieback, lack of flowers, and foliage yellowing, this virus also causes wilting.
It, too, is transported by western flower thrips and, like INSV, there is no cure. The only solution is to pull the plants and try to prevent thrips from infesting your plants in the future.
9. Verticillium Wilt
Verticillium wilt in dahlias is caused by Verticillium dahliae, and while dahlia is in the name, it can infect hundreds of other species, including cabbages, peppers, and melons as well.
The first sign that your dahlia is infected is usually wilting. But it’s not the usual type of wilting that you see when plants are underwatered during dry spells. Typically it will be just one stem or perhaps half of the leaves on a plant.
This wilting happens because the infection prevents the plant from taking up water.
As the disease progresses, you’ll see necrotic spots, yellowing or brown areas, and leaf drop.
Symptoms might also include “rosetting” and/or stunted growth. Rosetting is just a fancy way of saying that the internodes, or the part between the leaves, start to grow shorter than normal. This brings the leaves closer together, creating a “rosette-like” appearance.
Now for the bad news. The pathogen can live in the soil, on hundreds of plants, and on plant debris. Once it’s in your soil, it can stay there for years and years, just waiting for a new host to come along.
Growers have tried to breed resistant cultivars, but even these can succumb to the terrors of “vert” as it is commonly known.
To be sure that you’re dealing with verticillium wilt, you can send in a sample of the plant to your local extension office.
Once infected, the only thing to do is pull the plants and dispose of them. Then, don’t grow anything susceptible to verticillium wilt in that area for at least ten years.
Compared to some plants, like roses and hydrangeas, there are relatively few diseases that bother dahlias. But many of them are deadly or incurable.
So when your plants are infected, it’s bad news.
What symptoms are you seeing? Were you able to figure out what’s wrong with your dahlias? If you need additional guidance, please let us know how we can help in the comments section below. Photos help!
Now that you’re better equipped to keep your plants happy and healthy, you’ll need to learn a bit more about your dahlias. We have a bunch of guides that can help you expand your knowledge, including:
On March 18th, 2020, we closed our Brooklyn Heights shops, Salter House and Picture Room, along with just about every other business in New York City as the Covid pandemic swept through the city. We packed as much of the inventory as we could into our Volvo and settled in to quarantine at Meadowburn for an unknown length of time. [N.B.: See Sandeep’s Brooklyn apartment here.]
Like millions of others this past spring, we struggled to keep our businesses afloat, all while frantically navigating Zoom school and an unfathomable amount of anxiety. It was around this time that the Gerards asked us if we would like to join them in reviving one of the vegetable plots in the upper garden. I was thrilled.
Above: Me and my green bean joy! Photograph by Sita Bhuller.
Our first crop, sweet peas, failed. But after that, it was pretty smooth sailing! We fumbled our way through seedings, divided up watering and weeding duties, and formed friendships along the way. Soon enough, this Londoner, who has killed every house plant ever fostered and has not successfully grown a single sprout from seed since primary school Daffodil Days (and even then, her daffodils were always the weakest looking in the class), was sprouting everything she could get her hands on: tomatoes, spinach, lettuce, Brussel sprouts, watermelons, cucumbers, sage, and much much more.
I quickly learned choreography to seed the dirt and relished the hours spent in the garden. It was my time. The kids usually got bored after five minutes of following me around, and so would leave me in peace.
Above: A sampling of the crops we grew this summer.
As more of our crops came to maturity, we began to buy less and less at the grocery store. I became obsessed with preparing full meals solely from crops we had grown and felt immense satisfaction when I was able to achieve it. Gardening was fully nourishing, meditative—and absolutely practical. Any problems that arose could be literally weeded out, tossed onto the compost heap, or simply devoured and attempted again. As dilettante gardeners, there was nothing necessary, but something wholly precious, and certainly privileged about the whole endeavor.
Here’s how Ariella Chezar has been described in recent press: “a leader in the farm-to-flower movement” (in Vogue); “the godmother of seasonal floral design” (by Erin Benzakein of Floret Flower Farm). And here’s how Ariella describes herself: “Florist, teacher, author, lover of growing things,” she wrote, when we asked for her bio. Obviously humble and undeniably excellent at her craft, the veteran floral artist, who splits her time between the Berkshires in Massachusetts and Hillsdale, NY, shares her thoughts today on the no-till book she references constantly, her struggles with bindweed, and the sun hat she has on repeat.
No Polkdot Gardens. I don’t like a garden that has too many different colors and plants, which results in something that doesn’t allow the eye to rest.
Plant that makes you want to run the other way:
Dyed flowers.
Favorite go-to plant:
Clematis.
Plant that makes you swoon:
Philadelphus. It is so beautiful and divinely fragrant. In its season, I always have a sprig of it next to my bed.
Hardest gardening lesson you’ve learned:
Tilling, a.k.a. propagating bindweed throughout my field. I made the beginner mistake of tilling up a field that was full of bindweed, thereby propagating it. [Tilling can break up its roots into smaller pieces, which then leads to new plants.] It is one of the most difficult weeds to keep under control.
Favorite way to bring the outdoors in.
Above: A loose, fluid arrangement of peonies that Ariella designed for a fundraiser in May for Berkshire Waldorf School (both she and her children attended the school).
Fill your house with plants, cut anything you love and place it around your house.
Above: Dahlias are Mexico’s national flower so they grow exceptionally well here.
Gabriela’s garden presently is 3/4 of an acre and it expands little by little. She started with a 1/3 of an acre (which was grass) and the landlord agreed to rent her more space over the time. Depending on the season, Gabriela grows mainly ranunculus and dahlias, but she also cultivates sweet peas, hellebores, poppies, phlox, cosmos, larkspur, and foxgloves. When dahlia season ends, she turns her attention to celosia and cosmos, and snapdragons and sunflowers, too. Gabriela has her eye on Echinacea pallida ‘Hula Dancer’, which she will try out soon.
Above: Gabriela shares, “No garden will flourish without love and care.” Every inch of her garden cultivates her spirit and nurtures her soul, from the casual stone pathway to the infinite number of petals.
Anyone who grows their own cut flowers knows just how rewarding, convenient, and cost-saving this process can be. On a practical level, Gabriela adds, “When you grow your own flowers you get to choose the best stage to cut them and you have flowers that actually last longer. You can also have curvy stems and not very standard stems. The flowers that you grow in the garden have more personality and so the arrangement will be more special.” On a more spiritual level, “growing flowers can really change the way you feel in life and can remind us that we are part of an amazing universe and an infinite intelligence that created all the beauty surrounding us to show us its love,” she says.
Above: (left) A prolific pink Chrysanthemum will add tantalizing texture to an arrangement and (right) delicate cosmos, grown from seed, will add an airy, romantic touch.
Of course successful home-grown flowers take experience, trial and error, and a bit of serendipity. For anyone who is intrigued about venturing into this self-sufficient world, Gabriela shares this tip: “Raised beds are always good, also amending the soil and having a drip irrigation system. But, more importantly, love and care for them every day. Flowers respond to our energy and care.”
These structures contain all the energy needed to sprout.
In areas with spring rain, tubers sprout when the air warms and the soil is moist.
Gardeners in dry regions should moisten the earth until it is damp to simulate nature’s reawakening and continue to keep it evenly moist but not wet through the sprouting period.
Once the first green leaves appear, the gardener’s job becomes one of constant vigilance and judgment.
Routine Hydration
The production of fresh foliage indicates that the roots are actively nourishing and hydrating the plant.
From when the tubers first sprout through the end of the growing season, you’ll need to water just enough to keep the soil damp but never oversaturated.
Excess wetness and waterlogged soil causes the tubers to rot.
Dahlia varieties range from dwarf cultivars with petite one-inch blossoms to behemoth dinner-plate-sized blooms atop five-foot stalks.
The larger the specimen the deeper the roots, and so the plants have a greater need for water. Use a moisture meter as your guide and hydrate when the top inch of earth is dry.
These plants require deep soaking when you water them.
The best time to do so is in the morning before the day heats up; aiming the hose at the soil level delivers moisture to the roots and avoids wetting the foliage which can lead to fungal issues.
Plants require greater quantities of water as they grow more foliage, buds, and blooms.
In areas where rainfall is not likely to be enough to sustain the foliar development and blooming of garden flora, use a moisture meter and soaker hose irrigation system to hydrate slowly and evenly several times a week.
The great challenge is that, unlike a container that drains, garden soil may become oversaturated, causing water to pool and tubers to rot.
Consider adding a two- to three-inch layer of loose mulch around, but not touching, the stems to aid in moisture retention and facilitate drainage.
For potted specimens, use a moisture-retentive medium that drains well, a vessel with an ample drainage hole, and irrigate with a watering can.
Check pots daily, soak them once or twice a day during summer’s peak heat, and remove the saucers below to ensure the excess water drains away.
Additional Water Applications
In addition to breaking dormancy and routine hydration, you may need to supply supplemental water when transplanting, treating for pests, during times of extreme heat, and winterizing.
Transplanting
Spring is the time to transplant your overwintered tubers into the garden. Moisten the soil lightly to avoid rotting the tubers.
Use a moisture meter or your finger to judge when the top inch of soil is dry and hydrate regularly for the rest of the growing season.
Treating for Pests
Dahlias are prone to infestations of aphids, mites, and thrips, sapsuckers most prevalent in dry conditions. Keeping your plants hydrated increases their resistance to such pests.
You can also use a firm spray of the hose to dislodge visible insects.
Hose early in the day to prevent the foliage from remaining wet for long periods and reduce susceptibility to fungal diseases like powdery mildew.
Even after morning watering, during hot weather the foliage may wilt on an oppressive summer afternoon.
Use the mist setting on your hose and lightly spray the foliage. With the mercury at 90 to 100°F, the heat immediately evaporates the moisture and cools the leaves.
After digging them up at season’s end, rinse the tubers with a hose and let them air dry in the sun before packing them away in paper bags in a cool, dark, dry, rodent-free location.
You don’t need to give the tubers any water during the winter months while they are in storage.
Dahlia Divas
Successful growers learn early on that catering to moisture needs on a daily basis is the secret to exquisite blooms. They thrive on the challenge and revel in the rewards.
If the idea of soaker hoses and judging ground moisture seems daunting, consider growing dwarf varieties in containers.
You’ll need to water more often but are less likely to err on the side of oversaturation if you use a moisture meter, moisture-retentive, well-draining growing medium, and ensure your pots have drainage holes.
How do your dahlias grow? Share your experience in the comments section below.
When it comes to fungal diseases in dahlias, there are some really nasty ones to contend with.
Botrytis mold and root rot can kill your tubers quickly, and without much warning. Damping off can stop your seedlings in their tracks.
Powdery mildew, on the other hand, is more of an aesthetic problem.
It doesn’t usually kill the plant because the fungus can’t survive without living plant tissue. It’s to the pathogen’s advantage to keep its host alive.
We link to vendors to help you find relevant products. If you buy from one of our links, we may earn a commission.
Still, that doesn’t mean we want the distorted leaves, stunted growth, and ugly mildew to mar our plants.
In this guide, we’re going to discuss powdery mildew in dahlias and what to do about it.
Here’s what I’ll cover:
What Causes Powdery Mildew?
As I mentioned, powdery mildew is a fungal disease. It’s caused by Erysiphe cichoracearum and E. polygoni.
These pathogens are obligate parasites, which means they can’t complete their lifecycle if they don’t have a living host. As such, they can only reproduce on plant tissue, though the sexual spores (ascospores) can overwinter plant debris.
The spores need some humidity to germinate, but free water can actually kill them.
The disease is most active when temperatures are warm, typically between 59 to 82°F (15 to 28°C) and the humidity is relatively low, under 60 percent.
This usually occurs in the early summer when spring rains have stopped, and the air has started to dry out.
The asexual spores, known as conidia, can spread on the wind, so a nice dry day with a good breeze is ideal. Well, ideal for the disease spread, not for dahlia lovers.
The spores can also spread via insects like aphids.
The fungal species that cause powdery mildew in dahlias don’t infect all plant species.
If one or more of these plants is symptomatic in your garden, powdery mildew could easily spread to your dahlias.
Symptoms
Powdery mildew is one of the easier diseases to identify because the word “powdery” in the name refers to a white or gray powdery growth that appears on the leaves, stems, and flowers.
Look for symptoms like powdery circular patches or spots on the foliage. Usually, these spots appear on the top of the older leaves, first.
Rarely, you’ll also see the powdery material on the stems or flowers.
The texture is often compared to a dusting of flour or talc, and that’s a pretty good description, though it often looks more like dirty flour that has been dropped on the ground, scooped back up and dusted all over the plants.
This powder is the fungal structure and is anchored into the plant’s cells via haustoria.
When a part of the plant is heavily infected, it might turn yellow or brown and shrivel up.
And because the plant isn’t able to photosynthesize as well as it could if it had more foliage, the growth and flowering might be reduced in extreme cases.
Extreme cases might also cause the shoots to emerge deformed.
Prevention
Powdery mildew can be controlled and dramatically reduced, but it’s nearly impossible to eliminate Erysiphe in the garden once it arrives.
The fungal pathogen is adaptable and can manage to stick around even if you suppress it, just waiting for the right conditions to reinfect its preferred species.
The best tactic to keep your plants healthy is to prevent this disease from attacking your dahlias in the first place.
Despite the fact that the spores travel on a nice dry wind, they need humidity to germinate. Reducing humidity by keeping plants appropriately spaced, and pruning if they begin to get really crowded can help with this.
Plant in an area with adequate sun, since the disease is prevalent in shady spots.
If you’ve dealt with powdery mildew in the past, preventative treatment with milk, sulfur, or copper can keep you ahead of the game. We’ll talk about these options next.
Treatment
If powdery mildew infects your dahlias, prune off the worst of the infected plant material and nab yourself two different sprays from this list. I say two because I find that alternating treatments works much better than sticking to just one.
For light infections, one treatment method might be enough, though.
Believe it or not, milk is pretty darn good at treating powdery mildew. It works best on minor infections or when alternated with another treatment.
Mix nine parts water and one part milk together to create a 10 percent solution and then saturate the plants.
For heavier infections, you can increase the ratio to 50 percent milk.
Sulfur is another effective treatment. It kills many different species of fungi, including our friend Erysiphe.
Mix according to the manufacturer’s directions and spray it on the plant once every three weeks.
Alternate with a second treatment after the third week, or spray with sulfur again. Continue treatment until the symptoms are gone and no new symptoms emerge.
If you don’t already have some on hand, visit Arbico Organics to nab a 32-ounce ready to use, 16- or 32-ounce hose end, or 16-ounce concentrate.
You Have the Power to Stop Powdery Mildew
As far as plant diseases go, powdery mildew is not one of the worst infections you can bump into.
Since the pathogen isn’t trying to kill its host, you don’t have to worry so much about losing a beloved plant. But that doesn’t mean it won’t cause stunted growth or make them look ugly.
The biggest piece of advice I can give you is to check your plants often and take action the second you see any sign of a problem.
Are you having trouble with your dahlias? What symptoms are you seeing? Let us know what’s going on in the comments section below and we’ll see if we can help.
Growing dahlias requires patience. They don’t simply pop up in spring with their big, brilliant flowers.
Instead, the plants slowly develop over the summer until you’re finally rewarded with a colorful display that’s incomparable.
All that slow development leaves lots of time for something to go wrong.
Sometimes, along the way, your plants may start to look funky. Maybe you’ll see distorted growth, or perhaps there’s strange yellowing of the leaves.
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If you see these symptoms, it’s possible that dahlia mosaic virus has found its way to your garden.
If that’s the case, the news isn’t good. This disease is incurable, but if you identify it quickly, you can take steps to save the rest of your dahlias that are as yet unaffected.
So as much as you might want to stick your head in the sand and hope that dahlia mosaic virus goes away, you’ve got to learn how to identify this issue and what you can do to address it.
In this guide, we’ll go over the following to help you do just that:
What Is Dahlia Mosaic Virus?
Dahlias can be infected by numerous viruses, but one of the most common is dahlia mosaic virus (DMV).
It’s a pathogen in the Caulimovirus genus, with the binomial C. dahliae. All of the species in this genus rely on live plants as hosts. It is the only DNA virus to infect dahlias.
Photo credit: Anette Phibbs, WI Department of Agriculture, Trade & Consumer Protection, Bugwood.org.
Not sure what that means? There are two common types of viruses that infect plants: DNA and RNA.
The difference doesn’t really matter to those of us just trying to grow our flowers, but it’s worth noting that DNA viruses tend to evolve more rapidly and, as a result, evade our control strategies.
There are numerous strains of dahlia mosaic virus, including DMV-D10, DMV-Holland, DMV-Portland, dahlia common mosaic virus (DCMV). A single plant can be infected by multiple strains at the same time.
A single plant could also be infected by another type of virus, including tomato-spotted wilt, impatiens necrotic spot, cucumber mosaic, or tobacco streak viruses. These can cause similar symptoms to DMV.
Identification
One of the more challenging aspects of dahlia mosaic virus is that it’s difficult to identify.
Sometimes, an infected plant may show no symptoms at all, while other plants might have every symptom imaginable.
Photo credit: Anette Phibbs, WI Department of Agriculture, Trade & Consumer Protection, Bugwood.org.
One of the most common symptoms is stunted growth, where the plant just doesn’t seem to grow well no matter what you do.
Plants infected early in the year tend to be the most stunted. Those with stunted growth might not bloom at all, or will have few, small blossoms.
It also causes leaf discoloration in several different ways. You might see mosaic patterns on the foliage, or the leaves will lose color in patches and turn chlorotic along the veins. Sometimes, the chlorosis will appear randomly along the leaf blade.
Chlorosis over the entire leaf surface is likely to be the result of a nutrient deficiency, as dahlia mosaic virus shows up as spots of chlorosis.
The veins might lose color, known as vein clearing. Or, they might exhibit vein banding, which is when dark bands of color appear next to the veins.
And it’s not just the leaf coloring that is impacted, the flowers can be discolored as well. Flower discoloration might include breaking, which refers to the appearance of streaks or stripes on some petals, splotches, or fading.
The virus might also cause distorted leaf, stem, or flower growth, which might show up as twisted, curled, crinkled, or otherwise funky forms.
Finally, you might see necrotic lesions on the leaves and/or petioles, which are brown or black areas of dying plant tissue, usually in the form of spots.
The only way to be certain you are dealing with a virus and which virus is infecting your plants is to send or take a sample to your local extension office or diagnostic lab.
Many extension offices and labs will test your sample for free or at a very low cost, as it helps them track where the problem is popping up. So don’t hesitate to take a sample, that way you can be sure of the specific issue.
Biology and Life Cycle
Nobody likes aphids or thrips, to begin with, but here’s another reason to eradicate them from your garden. These common garden pests play host to the virus and can transmit it between plants as they feed.
The virus can also be carried in infected seeds or tubers, making it all the more important to buy from reputable sellers.
Once the virus finds a host, it begins reproducing. Then, it waits for a friend to carry it to a new host, whether that’s you dividing your plants or a pest that feeds on an infected plant.
Organic Control Methods
Since there is no cure for dahlia mosaic virus, controlling its spread is key.
First of all, always, always, always clean your tools between plants. Not just between working on your dahlias but any other species as well.
You can scrub them under hot water with some soap, or wipe them with a 10 percent bleach solution.
I will sometimes take a cup with me into the garden when I’m doing a lot of pruning. That way I can wipe my tools between each plant without having to run back into my house and do a thorough cleaning each time.
You can also use Virkon S, a veterinarian and farm biosecurity product that you can usually find at farm supply stores.
While the disease can sometimes be hit-and-miss in the garden for reasons not yet understood, decimating one plant and leaving another untouched, there are currently no consistently resistant cultivars available.
Physical
Sadly, since there is no cure, you can either live with the problem, knowing that it will probably infect all of your dahlias and maybe your neighbor’s, too or you can choose to remove the infected plants.
This is the preferred “treatment,” since it helps reduce the virus’ presence overall and won’t threaten other nearby growers.
The American Dahlia Society advocates for a policy of “if in doubt, throw it out.”
At a minimum, never propagate seeds or tubers from infected plants. The resulting plants will definitely be infected with the virus.
If you are growing dahlias for cut flowers, you can use floating row covers to keep the aphids out.
Biological
Predatory mites can help control thrips and aphid populations. Amblyseius cucumeris works best in temperatures under 90°F, and A. swirskii works well when temperatures are above that.
A healthy population of green lacewings (Chrysoperla rufilabris), assassin bugs (Zelus renardii), and minute pirate bugs (Orius insidiosus) can also help keep thrips and aphid numbers under control, reducing the incidence of transmittal.
You can introduce these garden helpers by purchasing them at retailers that specialize in pest control.
If you start to see aphids and thrips arriving in your garden, spray your plants with insecticidal soap.
This carries a low risk of harming beneficial insects and can dramatically reduce aphid and thrip populations.
The catch is that it’s not as effective once populations build up. You need to use it the second you see pests appear early in the growing season.
Spray your plants once a week for up to a month, but don’t rely on insecticidal soap alone if you already have a massive population, and don’t spray on windy days or when you can see lots of pollinators in the garden.
Chemical Pesticides
Keeping aphids out of your garden is impossible, and pre-treating your dahlias for pests doesn’t help.
These pests can still land, feed, and then fly off to die. Meanwhile, they’ve already left the virus behind. But you can limit how many are in your garden spreading diseases and draining your plants like little vampires.
While you should generally reserve chemical pesticide control for vital commercial crops, if you’re feeling desperate because you keep losing flowers to this disease, a product that contains cyantraniliprole can be an effective way to reduce aphid, spider mite, and thrips populations.
Use it as a soil drench starting early in the growing season and regularly until fall.
You can use this in addition to the biological methods mentioned above.
Don’t Go Viral
The presence of dahlia mosaic virus might make your heart drop, but look on the bright side.
Once you experience it, you’ll know better how to avoid the problem in the future and you can get ahead of the situation next time.
What symptoms are you seeing on your dahlias? Share with us in the comments so we can help other sufferers.
Sauvie Island, one of the largest river islands in the country, is just a quick drive from Portland, OR. Known for its mix of farmland and wildlife refuge, the island offers a wealth of adventure for birders, kayakers, beachgoers, and folks wanting to visit farms. One particularly nurturing and multi-faceted farm is the 5-acre Island Farm Studio. Led and founded by talented farmer, photographer, art director, and mother Christine James, this creative and florific property is completely women-run. The farm grows a variety of herbs, grasses, annuals, and perennials for cut flowers and natural dyes; it also boasts a refined culinary garden from which the freshest produce is picked for farm-to-table events. With a focus on sustainability, land restoration, and regenerative farming, Island Farm Studio hosts workshops and conservation-based classes as well.
Above: The farm at golden hour.
Christine grows all her plants from seed, and while this can be challenging and unpredictable, this method is not only cost-effective but also offers her a wider variety of options, which is essential for large-scale cut flower production. She and her team prioritize organic practices by avoiding toxic chemicals for weed and pest control. “Our methods include manual weeding, planting trap and companion crops, and hand-picking pests.” Bees also play a crucial role as pollinators in the farm’s ecosystem.
Above: Christine loves poppies for photographing and dahlias for flower bouquets.
While choosing a favorite cut flower is always a delightful challenge, Christine says, “As both a commercial farmer and an artist, my favorites vary depending on their purpose. For commercial flower farming, I prioritize ease of harvesting, vase life, and freshness at market.” Her top choices for market flowers include ball-shaped dahlias, apricot peony asters, lisianthus, snapdragons, and marigolds for their beauty and sturdiness. “For botanical portraiture, I adore working with English roses, delicate poppies, lacy sweet peas, peonies, and feathered tulips, each possessing its own romantic charm.” For making natural dyes, Christine cultivates a variety of flowers, including indigo, marigolds, coreopsis, tango cosmos, and black knight scabiosa.
Above: Christine has made it a priority to create an inclusive environment at the farm.
Farming and photography have been transformative for Christine. “My journey with flowers began as a means of creating a sanctuary for myself and my children after surviving domestic violence. Flowers have been integral to my healing, artistic expression, and agricultural journey,” she shares. “Through photography and farming, I’ve found language for my experiences. (You can view her latest exhibit, “Flowers Pressed,” on her web gallery.) The farm gifts her with ample blooms to photograph and create bouquets from, but it has also taught her invaluable lessons. “Balancing fiscal responsibility, year-round work demands, and preventing burnout are constant challenges here,” she says. Wisely, she makes it a priority to carve out spaces solely for personal joy. Christine adds, “Humility in recognizing the boundless mysteries of the natural world and the importance of respecting and listening to Mama Earth are ongoing lessons.”
Above: This season, Island Farm Studio is focusing on fostering accessibility. “We aim to create a safe space for community members and artists to connect with nature through events like outdoor gallery evenings showcasing local artwork inspired by the land.”
When my friend and colleague Margot Guralnick and I set out to write The Low-Impact Home, we had many discussions with Remodelista founder Julie Carlson about whether our project would be a beautiful coffee table book or a nuts-and-bolts manual for eco-minded homeowners. What we realized was, we needn’t sacrifice one for the other. Our book would be equal parts inspiration and information.
When I opened up Beyond the Meadows: Portrait of a Natural and Biodiverse Garden by Krautkopf, in bookstores now, I immediately recognized in it the same desire to both inspire and edify. That the book is brimming with gorgeous images isn’t all that surprising given its authors, German homesteaders Susann Probst and Yannic Schon, are professional photographers. What is unexpected, and delightful, is how much they’ve chosen to share about their experience as new homesteaders. The two really get into the weeds, if you will, of how they designed their landscape, cared for their plants, welcomed biodiversity, naturally enriched the soil, and, ultimately, became self-sufficient. Diagrams, before and after shots, and plant lists help tell their gardening journey. And they’re blessedly not shy about revealing their mistakes, either.
Above: Susann and Yannic’s homesteading journey started in 2018, when they moved from Berlin to a small cottage with lots of land in a village in northeastern Germany. It was built as a “settler’s house,” one of many that cropped up post-WWII to encourage people to become more self-sufficient. Their new book, now available in English, documents their experience working the land as new gardeners.
“To be honest, we held back from writing a gardening book for a long time,” Susann tells us. “We felt we were only at the very beginning of the learning process and therefore didn’t feel ready. However, at one point we realized that this gardening journey would never end and that we would constantly be learning new things that would be worth writing about. So there would never be the ‘right’ time to start.” The results are less guidebook and more garden memoir. “We wanted a book full of beauty and inspiration, which would nevertheless contain our knowledge and experiences from the past five years,” she says.
Susann and Yannic’s garden appeared in The Low-Impact Home—Margot and I were enchanted by their property and their commitment to ecology-based gardening—so I read their book with great interest. But even if you don’t know a thing about them and don’t harbor any fantasies about growing your own food, Beyond the Meadows is a must-read. It’s for anyone curious about how to be a better gardener or adopt more planet-friendly approaches—and also for those who simply yearn to slow down and smell the earth.
We are longtime admirers of English writer, cook, and gardener Sarah Raven, so we were super-excited to learn that her newest book, A Year Full of Pots, is now in bookstores. In this how-to guide on all things container gardening (the third installment her series that includes A Year Full of Flowers and A Year Full of Veg), she gives detailed instructions for planning and planting in pots for each month of the year, along with color groupings, tips for what to plant where and when, and detailed plant lists with stunning photos of her own pot-filled garden at Perch Hill.
Above: An overhead view of the Oast Garden, teeming with potted plants, at Perch Hill in spring.
Raven makes it easy for neophytes and experts alike to create a beautiful container garden, no matter the size. Here are six tips from her book on how to capture ebullience and beauty in a pot.
Above: Raven planning her garden with pencil and paper.
Pot planning goes old school. While there are plenty of fancy online garden planners, there is a wonderful satisfaction that comes with pencil and paper. Raven recommends sketching out the bones of your garden, the spaces, hardscapes and major plants and then overlaying tracing paper (or even baking parchment) and then cutting circles to represent your pots and arranging them where you think you’d like the pots and plants to go. Pro tip: She recommends cutting out photos of the plants you’re considering to make sure you can visualize the best you can what the garden will look like in real life.
2. Plan for a Bride, Bridesmaid, and Gate-crasher.
Above: This pot features tulips ‘Muriel’ as the Bride, ‘Nightrider’ as the Bridesmaid, and ‘Orange Favorite’ as the all-important color-contrasting Gatecrasher. Photo by Jonathan Buckley.
Raven breaks down one of the more complicated challenges in deciding what plants go into the pot in regards to choosing a color combination. Think about the colors as the Bride, Bridesmaid and Gatechrasher, she says. The Bride is the center of attention, the one that gets all the focus. The Bridesmaid plays a supporting role in the pot, as one would play in real life—same color as the bride but not as showy. Finally the Gatecrasher adds a bit of drama with contrast. Pro tip: Get some paint chips and play around with them to see what color combinations work together.
above: An example of some of the Boiled Sweet color palette.
For those who need a bit more guidance, Raven even provides specific color palettes to try: Dark & Rich, Boiled Sweet Brilliant, Warm and Soft, and Soft and Cool. Included are extensive photos for each palette for easy reference.
3. And don’t forget the Thriller, Filler, Spiller, and Pillar.
Above: Dahlia ‘Totally Tangerine’ with Salvia ‘Amistad’ and Panicum elegans ‘Frosted Explosion’ syn. Agrostis ‘Fibre Optics’ syn. Panicum capillare ‘Sparkling Fountain’ in a metal container. Erigeron karvinskianus grows in the terracotta pot.
