Tag: Gladiolus

Gladiolus, aka sword lilies, produce showy flowers with sturdy stems, popular for cutting and vase arrangements. They grow from flattened bulbs called corms.

They thrive in full sun with moderate moisture and rich, well-draining soil. Mature dimensions are 18 to 72 inches tall with a spread of 12 to 24 inches.

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The corms are tender bulbs that are winter hardy to Zone 7. In colder regions, gardeners enjoy them as annuals and dig them up for winter storage.

Our guide to planting and growing gladiolus has all you need to enjoy plants at your house.

This article discusses how to lift, cure, and store the corms to replant in the spring.

Here’s what we’ll cover:

Let’s get started!

Ready to Dig

When summer draws to a close and the nights grow cooler, gladiolus blooms fade and the foliage begins to wither; it’s time to dig up the bulbs.

While a light frost may not harm them, a hard freeze could be deadly.

You’ll need gloves, a long-handled shovel or pitchfork, a hand-held trowel or claw, and pruners.

Sanitize all metal parts with a solution of one part bleach to nine parts water, rinse, and air dry before use.

Lifting and Curing

Wear gloves when handling gladioli, as the corms are toxic, and contact with the skin and digestive tract is best avoided.

You will need a long-handled shovel or pitchfork that enables you to use foot pressure for easy digging.

Use your foot to insert the shovel or fork straight down into the ground about six inches away from a clump of foliage.

Push the handle down toward the ground to gently loosen the soil.

Work around the leafy clump using the same insertion and lifting motions until you have detached and raised a mound of soil.

Use a handheld garden trowel or claw to remove the individual flattened bulbs carefully from the soil.

Brush off as much earth as you can, taking care not to remove the paper tunics that protect the corms. Do not wash them to avoid the risk of fungal development.

Use pruners to cut off the foliage, leaving a two-inch portion attached to the top of the corms. Cut off the roots, taking care not to nick the underside of the corms.

Once unearthed, the tender bulbs need to “cure” or dry before you place them in storage. Discard any that are discolored, soft, blemished, or shriveled.

Old, dried up corms and tiny fresh young ones may be attached to the large “mother.”

Remove any that are dried up and leave the young babies attached, so you can divide them in the spring before replanting, rather than risk rotting during storage from separation wounds.

Spread the corms in a single layer on newspaper or screens and keep them out of direct sunlight in a dry location with a temperature of 60 to 70ºF for three weeks.

Winter Storage

After the three-week curing period, examine the corms carefully and discard any that are damaged, discolored, shriveled, soft, or malodorous.

Remove dried up foliage and roots that have fallen off and brush off any remaining soil, taking care not to damage the paper tunics.

Before putting the bulbs into storage, it’s best to sprinkle them with a dusting of fungicide to inhibit fungal growth during winter storage.

I use Bonide Sulfur Plant Fungicide and it’s also an effective pesticide for ticks, mites, and fleas.

Bonide Sulfur Plant Fungicide

Bonide Sulfur Plant Fungicide is available from Bonide via Amazon.

To store your corms, you can either use clean, dry cardboard boxes or purchase ventilated plastic stacking crates.

If you plan to use ventilated plastic crates, here are some to consider:

These gray plastic crates measure 13.86 by 10.4 by 7.1 inches and have a volume of 15 liters.

Plastic Stacking Folding Storage Crates

They stack securely and are collapsible for folding and placing out of the way when not in use.

You can find them in three-packs available from Idotry via Amazon.

When you have your box or crate ready, line the bottom with one or two sheets of newspaper.

Set the corms in a single layer, ensuring that they aren’t touching each other.

Sprinkle your fungicide powder lightly over them.

Lay newspaper over the first layer and repeat the above process. Make sure you leave enough room so that the box closes without pressing on the corms.

The box lid or folded flaps should fit loosely so air can enter and circulate.

Instead of newspaper between the layers, the pros at the University of Wisconsin-Madison Wisconsin Horticulture Division suggest using two to three inches of coconut coir, peat moss, sand, sawdust, vermiculite, or wood shavings.

Store the box or packing crate in a cool, dry, rodent-free, well-ventilated location with a temperature between 35 and 45ºF and relative humidity of about 50 percent.

Check the boxes or crates regularly throughout the winter and discard any bulbs that shrivel up or become soft and moist. If you are using newspaper, change it if it feels damp.

Lift, Cure, and Store

Managing gladiolus over the winter months is easy after you do it once and know the drill.

Let’s recap:

• Lift the tender bulbs carefully with a fork or shovel and remove foliage, roots, and soil.
• Cure them in a single layer for three weeks in a cool, dry location to remove moisture.
• Store them in well-ventilated containers with a sprinkle of fungicide and newspaper or absorbent organic media between the layers so they don’t touch.

Now you know how to save corms from year to year. Be sure to add “Lift the Glads” to your garden planner so you remember to take them out of the ground before the first hard frost.

Do you lift your gladiolus for the winter? Please let us know how you store them in the comments section below.

If you found this article informative and would like to learn more about gladiolus, we recommend the following guides next:

Gladiolus is a genus of flowering perennials that produce colorful blooms on tall spikes during the summer months.

They grow from corms that readily naturalize in the landscape in Zones 7 to 11. In other regions, these flowers can be cultivated as annuals.

If your gladiolus plants are looking sickly or struggling to bloom, it’s not always because of sub-par cultivation practices – it could mean that disease has struck.

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If illness has come upon your flowers, you’ll probably notice it easily – a diseased gladiolus tends to look very sick. 

Whether the symptoms manifest on their blooms, leaves, stems, or bulb-like corms, sickly gladiolus plants won’t be bringing their aesthetic A game to your landscape. And when you’re expecting pretty flowers, a lack of them is pretty disappointing.

That’s why we’ve put this guide together. From symptom spotting to management methods to prevention pointers, you’ll learn everything you need to handle nine common diseases of Gladiolus.

Here are said diseases:

But before we dive in, I should mention that the best way to keep diseases from attacking your gladiolus is to cultivate your plants properly.

By selecting an ideal growing location and dialing in your care practices like watering and fertilization, your specimens will have the health and vigor to withstand many common pathogens.

If you need a refresher about how to grow and care for gladiolus, check out our guide.

And now, let’s discuss some diseases you may need to contend with.

1. Bacterial Leaf Blight

Yes, I know that “bacterial” doesn’t really narrow it down – a bunch of different bacteria can cause blight on leaves.

But in the case of gladiolus plants, leaf blight is caused by species of Xanthomonas, which lie dormant in plant detritus within the soil and can persist for many years.

You should stay alert during periods of excessive rainfall, as that’s when the moisture-loving Xanthomonas bacteria tend to strike.

When the pathogen infects a gladiolus plant, the foliage will develop small, elongated, and water-soaked spots between leaf veins. In time, they turn brown to black, with yellow margins.

The spots look pretty gnarly, and can also interfere with photosynthesis. To prevent infection, well-draining soil is essential, as well as removing any plant detritus that builds up in your planting areas.

Unfortunately, there’s no known treatment for this issue, so you should pull and destroy any symptomatic specimens, and dispose of any diseased-looking corms that you dig up at season’s end.

As the soilborne pathogens are long-lived, don’t replant gladiolus in the area for at least two years.

2. Botrytis Blight

Botrytis blight is caused by fungal species in the Botrytis genus, rather than bacteria.

These pathogens survive in bulbs and in plant residues.

Typically breaking out in cloudy, humid, and moist conditions in temperatures of 50 to 70°F, this disease causes flowers to turn a crinkly brown, leaves to develop tiny brown spots, and stems to develop soft, water-soaked lesions.

The plant tissues eventually decay and develop a coating of fuzzy gray mold.

Below the soil, the corms and roots can rot as well, becoming covered with black, seedlike sclerotia which produce spores that spread the disease. Eventually, infected gladiolus plants will die.

You can slow down disease development by pruning diseased tissues and removing spent flowers as soon as you see them.

Bonide Copper Fungicide

You can also treat your gladiolus with copper fungicide such as this one from Bonide, available at Arbico Organics.

If fungicide treatment doesn’t work, and the gladiolus plants continue to decline, dig them up and dispose of them in the trash, corms and all.

If you have had a problem with botrytis in the past, make sure you look for corms that are noted to have been treated with hot water and/or fungicides.

And ensure you space your gladiolus plants properly, rotate your gladiolus with other kinds of flowers each year, and avoid wetting the flowers and foliage when you water.

3. Curvularia Leaf Spot

Caused by species of Curvularia fungi, Curvularia leaf spot is fun to pronounce, but a total buzzkill to experience.

Spreading primarily via infected corms, the fungus causes leaves to develop white spots that resemble pinpoints, which later turn brown, rounded, and ringed with chlorotic tissue.

Eventually, spots can merge into larger blemishes that blight large areas of the foliage, hindering both aesthetics and photosynthesis.

Since this can be a problem with stored corms, it’s important to store them in the right conditions.

First, you’ll need to cure your corms by keeping them in a storage room kept at 95°F and at 80 percent relative humidity.

Set them in the location to cure for six to eight days, clean them, then cure them for four more days. Afterwards, keep them at 40°F and at 70 to 80 percent relative humidity until it’s replanting time.

Before planting, inspect the corms carefully and if you notice white or brown spots on any of them, dispose of them in the trash.

If you notice symptoms on the gladiolus growing in your garden, it’s best to dig them up and pitch the gladiolus plants as there is no cure.

4. Fusarium Yellows

Also known as Fusarium rot, Fusarium yellows is a nasty condition caused by the fungus Fusarium oxysporum f. sp. gladioli, which resides in infected corms and soil.

Thriving in temperatures of 70°F or warmer, this pathogen causes leaves to wilt, yellow, turn brown, and eventually die.

Flowers, if they develop at all, will be small and deformed, while the corms rot from the inside out and if you dig them up, you’ll see round, sunken brown spots.

If you notice any discolored or lesioned corms before you plant them, then they should be discarded. Same goes for any severely symptomatic plantings in your garden beds.

If you have had problems with this pathogen in the past, do not plant your gladiolus in the same location for at least five years.

5. Scab

Unlike a scab on your skin, this scab isn’t something that you should ignore.

Caused by species of Pseudomonas bacteria that reside in soil and on corms, scab leaves infected corms riddled with brown, round, and sunken lesions with raised edges. In time, they may ooze a nasty bacterial exudate.

The foliage will exhibit small, raised, and reddish-brown dots, which merge in time to form long streaks of necrosis. Eventually, the stem will rot at the soil line, and plants will die.

If you notice any infected leaves, prune them promptly. If infection continues and symptoms worsen, dig up and inspect the corm – dispose of any that show signs of rotting. If you notice that some corms are diseased prior to planting, discard those too.

Soggy soils, warm weather, and excess nitrogen create favorable conditions for the spread of this disease, so provide well-draining soil, monitor for symptoms during warm weather, and be careful when fertilizing nearby plants with nitrogen so that it doesn’t stray into the soil of your gladiolus.

Annual rotation with other flowers is helpful for prevention, as well.

6. Stemphylium Leaf Spot

Another disease that’s a doozy to enunciate, Stemphylium leaf spot is capable of causing some serious damage.

Thanks to species of Stemphylium fungi, this disease causes small, round, and yellow spots surrounding prominent red centers on the leaves.

In time, the foliage will wilt and turn yellow before dying back from the leaf margins inwards, until the entire gladiolus plant eventually dies.

As is often the case when dealing with fungal issues, the pathogen develops in warm, moist conditions, so well-draining soil is essential. Prune infected leaves when you notice them.

Applications of copper fungicide can be effective in the early stages of infection. But as with any diseased plant, it’s best to pitch it once it’s too far gone.

7. Storage Rot

The threat of disease isn’t gone when your corms are put away for the winter. If you store them wrong, they could suffer in storage just as they might in-ground.

Caused by Penicillium gladioli, this type of rot leaves stored corms soft and rotted, with greenish-blue masses of spores often covering the rotted parts. As you can imagine, corms infected with this fungal pathogen don’t yield the best flowers.

When you dig up your corms for the winter, you should only keep ones that are free from blemishes. It’s also essential to cure them properly, as moist conditions promote storage rot.

It doesn’t hurt to check your corms throughout the storage period – if you notice any symptomatic ones, remove and destroy them.

8. Stromatinia Dry Rot

Many rot diseases will leave plant tissues soggy and rotted. With this one, it’s more of a dehydrated and desiccated rot, Egyptian mummy-style.

Stromatinia gladioli is the fungus to blame here, and it can persist in infected soils for long, decade-plus periods of time.

When a corm is infected, it develops small, reddish-brown lesions which sink and turn black in time, often combining to form large patches of dead tissue. Corm husks will turn brown and crispy, while the corm as a whole turns corky and mummified.

Leaf bases turn brown and the foliage can turn yellow and resemble shredded paper. As the infection progresses, foliage drops and the plant dies.

Unfortunately, there’s no known cure once a gladiolus shows symptoms, so you should remove and dispose of any that are infected right away. Copper fungicide can help protect specimens that are not showing signs of infection.

After you have disposed of infected gladiolus plants, you can solarize the soil to kill any remaining pathogens and ensure the site is safe for future plantings.

9. Viruses

There are a number of different viruses that infect gladiolus plants, including mosaic and ringspot viruses.

Symptoms of viral infection include mottled leaves, ring-shaped leaf blotches, and gnarly-looking foliar streaks, which usually result in reduced aesthetics and plant death.

The viruses are usually spread by infected tools, feeding insect vectors, or both.

Since plant viruses are incurable, it’s best to destroy any gladiolus that show signs of infection to prevent transmission to nearby specimens.

Keeping on top of weeds and pests, and keeping your garden tools sterilized can help to keep viruses at bay.

It’s a Thrill When Your Plants Aren’t Ill

It may be obvious to say, but gladiolus plants look a trillion times better when they’re not sick.

Plus, it’s kind of a rush when the growing season arrives and you don’t have any sick plants to deal with.

And even if you do, at least you know how to manage them and prevent their spread in the future. Because that’s the difference between good and great gardeners: the ability to take problems and deal with them in stride.

Have you had problems with your gladiolus? What was the problem? Let us know in the comments section below, and if you’re struggling, feel free to submit a picture so we can help you out!

And for more information about growing gladiolus in your garden, check out these guides next:

If you’re anything like me, you spend at least a portion of the winter dreaming of the glory of the coming summer’s garden. I plan and plot, but most of the actual work won’t start until the spring.

But there are a few gardening tasks that I can begin during the winter months to get a jump on the growing season.

It gives me that gardening fix I crave, and it helps me to prepare my upcoming magical summer garden. Starting gladiolus corms early is one of those tasks that I look forward to.

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As late winter rolls around, I start planting so I can enjoy the colorful gladiolus flowers earlier than if I planted them directly outdoors.

This guide will give you the knowledge you need to start your corms and move them to the garden when the timing is right.

Here’s what we’ll go over with that goal in mind:

To be clear, gladiolus have corms, not bulbs. But many gardeners refer to them as “bulbs,” so we’ll being using the terms interchangeably in this guide.

Spring can’t come early enough, as far as I’m concerned. So let’s not wait one minute more!

Prepare the Corms

Four to six weeks before the last predicted frost date in your area, prepare the corms.

Whether you purchase new bulbs to plant or you’re restarting some that you lifted in the fall and kept in storage, you need to prepare them for planting.

Some retailers won’t carry gladiolus during the off season but others have them in stock, so if you’re buying new, it pays to shop around.

‘Impressive’

Dutch Grown, for example, carries a fantastic range, from the multi-hued pink, fuchsia, and pale salmon ‘Impressive’ to the blood-red ‘Black Star.’

‘Black Star’

Or maybe you want a mixture of colors. If so, visit Burpee for a Glamini mix in yellow, red, purple, and white.

Glamini Mix

Brush off any dirt from the overwintered bulbs with a soft, dry brush. Divide up any large clumps. Purchased bulbs should be clean and already divided up for you.

You can optionally set the corms in water overnight to encourage them to open up and start growing.

Either submerge them entirely or just set the base in the water. This just speeds up the sprouting process, but it’s not essential.

Planting

Fill a flat or a container that’s at least eight inches deep with fresh, water-retentive potting mix.

If you have lots of gladiolus corms, consider using a large storage bin – 18-gallon or larger. Just remember to put it in place before you start filling it up, because it’s going to be heavy to move.

You might even want to put the container on casters or in a wagon if you don’t have friends around to help you haul it.

Plant the corms approximately two to four inches deep, depending on the size, as you’ll want them twice as deep as the length of the corm. Make sure the pointy end is facing upwards.

Water the medium well so that it’s moist but not soaking wet or soggy.

Care

Place the container in a warm, sunny spot indoors that receives at least six hours of direct sun and keep the soil moist.

You can also use supplemental lighting if you don’t have an area with enough exposure.

Allow the top inch of the soil to dry out between watering.

Be cautious if you’re using a large storage container, because it’s easy to add too much water to the point where the soil starts becoming soggy at the bottom of the container, which can lead to rot.

Within a few weeks to a month, you should see new growth popping out of the soil.

Moving Outdoors

Once the nighttime temperatures are at least 60°F and the gladiolus plants have at least three leaves, you can bring them outdoors.

Before you can put them in the soil and soak up the beauty, you need to harden the plants off as they’re used to the easy life of an indoor environment.

To harden them off, take the growing container outside and set it in or near the spot where the gladiolus will eventually be planted. Leave the pot there for an hour and then bring it back inside.

The next day, leave it out there for two hours before bringing it in.

You’re going to need a helper with a strong back if you used a large storage container! You can probably skip ab day after the workout you’re going to have.

Keep adding an hour each day until the plants can stay outside for a full eight hours.

At this point you can transplant your gladiolus.

Prepare the planting area by digging enough holes for all your corms. It’s better to dig a larger hole than you think you’ll need so you don’t have to try and wedge the corm into it.

Gently push your hands into the soil and dig down underneath the roots of each plant. You can also use a trowel, but I like to use my hands because I can really feel the root system and it helps to avoid damaging the roots.

Lift the gladiolus out of the soil and place it in the ground. The corm should be sitting at the same depth as it was in the growing container. Repeat until all your corms are in the ground.

Firm the soil up around the corms and water in well. You might need to add a little more soil if it settles.

Visit our comprehensive guide to growing gladiolus for tips on how to grow and care for this ornamental beauty.

Start the Party Early

If you can’t wait for spring to get started, starting gladiolus indoors will give you the leg up you’re craving. You can use this method for other non-hardy bulb species like cannas and dahlias.

What are your big garden plans this year? Will you be blending your gladiolus with other flowers? Are you growing a cut flower garden? Share in the comments section below!

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