Impatiens hawkeri
Impatiens are incredibly, amazingly popular. I challenge you to walk into a nursery or home goods store during the spring or summer and not find at least one flat of them.
But these plants are primarily used in shaded areas, leaving sunny spots out of the game.
And then there’s the whole downy mildew situation. In some areas, it’s a matter of when, not if, your impatiens will be decimated by the rapidly-spreading disease.
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Enter New Guinea impatiens. They look similar to the species we’re familiar with, but they’re impervious to downy mildew.
Plus, they grow well in full sun. They look similar to one another, but the New Guinea species is larger overall, with larger leaves and flowers.
There’s much more to know about these floriferous marvels and we’ll discuss all the goods, coming up. Here’s what we have in store:
New guinea impatiens (Impatiens hawkeri) aren’t as common as their close relatives, ornamental impatiens (I. walleriana), but they’re rapidly gaining in popularity.
That’s because, as we mentioned, they’re resistant to the downy mildew menace that is decimating common impatiens.
But they also have larger flowers, bloom for a good long time, are self-cleaning, and can adapt to full sun or full shade, if given the water they need.
Cultivation and History
New Guinea impatiens were introduced into the North American commercial market in 1972.
Since then, they’ve grown in popularity and have been used to hybridize with common impatiens to create sturdier plants.
As their name suggests, they originated in Papua New Guinea in hot, humid forests. People there have been cultivating these flowers for centuries.
Specimens collected by Lieutenant J. D. Hawker of the Royal Navy were sent to the Adelaide Botanical Garden in Australia in 1884 by Richard Schomburgk.
Schomburgk, the curator of the botanical garden, pressed a few plants and shipped them to the Royal Botanic Gardens at Kew, in England, where the species was then named and described by botanist William Bull.
Over the next few decades, they gained rapid attention and became popular garden and houseplants in England and Australia.
In the 1970s, the US Department of Agriculture sponsored an exploration of Papua New Guinea to find new ferns, begonias, and rhododendrons.
H. F. Winters and J. J. Higgins of the Agricultural Research Service found those, but they also spotted some impatiens.
While only 25 of the specimens survived the journey back to the US, after a quarantine period, the USDA took cuttings and sent them to botanical gardens, universities, and researchers to use in breeding programs.
That breeding effort has produced some really exceptional plants, with dense growth, stunning blossoms, and even some variegated cultivars.
Some have reddish, nearly black leaves, and some have multicolored blossoms.
Propagation
Professional growers typically propagate these plants from softwood cuttings, so that should tell you how reliable this method is.
You can also propagate from seed or purchase starts at a nursery.
Regardless of which method you choose, pinch the propagules frequently above a leaf bud after they begin putting on new growth. This will encourage fuller, bushier growth.
From Seed
Growing impatiens from seed is a little bit challenging. The seeds lose viability rapidly, so try to purchase from sellers who list a harvest date or guarantee fresh seeds until a defined date.
The seeds need light to germinate, so fill a seed tray with potting soil and sprinkle the seeds over the top.
You can press them in gently, but don’t bury them at all. Place the tray under grow lights for at least eight or up to 12 hours per day.
After the seedlings germinate, thin seedlings to four inches apart and gradually move the lights away from the leaves.
Generally, the lights should be about three inches from the top leaves, but this can vary a little depending on how intense your lights are.
Look for yellowing of the leaves. This can be a sign that the lights are too close.
From Cuttings
Cuttings are the most common option for reproducing impatiens, and no wonder. It’s so easy.
In the spring or summer, take a four-inch cutting from a healthy specimen. Make the cut just below a leaf node.
Place the cutting in a cup of water or a 50:50 mix of moistened peat and vermiculite and set it in an indoor location that receives bright, indirect light.
Keep the potting mix moist or change the water every day.
New roots should develop within two weeks. If not, you’ll need to try again. To test whether a cutting planted in soil has roots, just give it a gentle tug. If you feel some resistance, you’re golden.
Once you have one-inch roots on your water-grown cuttings, pull them out of the water and sprinkle them with a light, fluffy potting medium. This prevents the roots from clumping together.
Place each cutting in its permanent pot filled with potting medium, or in the ground.
Before you transplant, make sure you’ve amended the soil with lots of well-rotted compost to make it fluffy and light.
From Seedlings or Plugs
Most gardeners start their impatiens journey by purchasing plugs, seedlings, or larger transplants. If you go this route, it’s fairly easy. You can transplant in containers or in the ground.
If you opt to grow in a container, choose one with drainage holes and fill it with water-retentive potting soil.
For in-ground growing, loosen up the soil a foot down. Dig up the soil and add equal parts well-rotted compost, soil conditioner, and/or well-rotted manure.
Mix it all together and fill the planting area back in. Then, dig holes the size of the containers that your plants are currently in, spaced 18 inches apart.
Gently loosen each plant from its pot and lower it into the hole. Firm the soil up around the transplants, taking care not to bury them deeper than they were growing in the nursery containers.
Give them some water so the soil feels moist but not soggy.
How to Grow
If you try to grow these plants in the same shady conditions that the walleriana species will thrive in, you’ll be disappointed.
New Guinea impatiens need full sun to partial shade. In full shade, they’ll offer up some great greenery, but they won’t flower well.
Try to give the plants at least three hours of direct light or six or so hours of dappled light.
Plants growing in full sun need lots of moisture. Much like fuchsias, these plants can do well in full sun, but only if the soil isn’t allowed to dry out.
I think that’s why some people labor under the idea that these plants can’t grow in full sun. They can, but they tend to dry out more quickly.
If you can’t provide oodles of water, it’s better to grow them in partial sun or partial shade instead.
If you live somewhere that gets extremely hot in the summer, plant somewhere they’ll receive shade in the afternoon.
New Guinea impatiens can’t tolerate drought one bit. When the soil starts drying out, the plants will wilt rapidly.
They need a lot of water, and the soil should always feel like a well-wrung-out sponge. Any drier and it’s time to add water.
Err on the side of wetter rather than drier, though it’s important to remember that this plant won’t tolerate standing water either.
All that said, breeders have been working to create drought-tolerant cultivars. Check the tag on plants at the nursery to find out if the ones you’re looking at are more drought-tolerant.
The soil pH should hang out right around 5.5 to 6.5, but they’ll tolerate levels slightly outside of this range.
Every month during the growing season, feed with a foliar or soil fertilizer with a higher ratio of phosphorus – P in the NPK formula of plant nutrients – which encourages robust blooming. Usually, you’ll find these sold as flower-specific fertilizers.
I like Down to Earth’s range of products because they’re all-natural and come in compostable boxes.
Down to Earth Rose and Flower Mix
Their Rose & Flower Mix is available at Arbico Organics in one-, five-, and 15-pound boxes.
Container growing doesn’t require any special care except to note that the soil will likely dry out much more quickly.
Growing Tips
- Grow in full sun to partial shade, but be aware that plants in full sun will need careful monitoring.
- Soil should stay consistently moist.
- Fertilize monthly during the growing season from spring to fall.
Maintenance
There’s no need to deadhead the flowers because they’re self-cleaning. As they age and fall naturally, the plant will keep producing more blossoms.
If they start to become leggy, just pinch them back. You can pinch them back by about half to a leaf bud and they’ll come back more lush and thick, with new blossoms.
There’s also no need to toss your plants if you live somewhere too cold for them to withstand in the winter.
They can be overwintered on a windowsill or another indoor spot with enough sun, or in a greenhouse. Trim the plant back by about half before moving it.
Either carry the pot to your chosen spot or dig up a clump of dirt that contains the root ball and pot it up in a container.
Reduce the amount of water you provide so the top inch of soil is allowed to dry out. Don’t feed the plants during the winter.
Cultivars to Select
Many New Guinea impatiens that you’ll find on the market are hybridized with other species, such as SunPatiens. In this case, they are a hybrid of walleriana and hawkeri parents.
Growers aimed to combine the hardiness and sun tolerance of the New Guinea types with the floriferous nature of common impatiens and the result was this popular plant.
Here are some excellent New Guinea impatiens worth checking out:
Celebration
The Celebration series offers extremely large blossoms on vigorous plants.
Colors in this series include pale lavender, lavender, salmon, white, pink, apricot, purple, rose, peach, orange, and red.
If you like to grow your impatiens in pots, this is a good option because one plant will rapidly fill up a pot 18 inches in diameter.
Cultivars in this series are more heat tolerant than most other New Guinea impatiens.
Celebrette
The lilac, fiery orange, pink, or striped pink and rose flowers of the plants in this series are truly eye-catching, but it’s the size that makes them extra exciting.
These have some of the largest flowers among New Guinea impatiens. They also start blooming a bit earlier than some others.
The plants stay extremely compact, growing to max heights just under a foot tall.
Divine
The Divine™ series was bred to be an alternative to the common impatiens we all know and love.
More shade tolerant than walleriana plants, they’re resistant to that awful fungus that is killing so many other impatiens. Cultivars from this series can be propagated from seed, which is exciting.
Many New Guinea impatiens are hybrids that won’t grow true from seed, or they’re patented varieties so propagation is illegal. But these have stable genetics, and you’ll often find seed available for sale.
Divine™ comes in pink, white, red, lilac, salmon, and violet.
Infinity
Plants in the Infinity® series are interspecific hybrids that have improved mildew resistance and the ability to bloom in deep shade.
The foliage on this foot-tall plant is beautiful, with deep green and purple hues.
These plants are extremely vigorous and will bloom continually until the frost, or they’ll keep blooming if you live in a frost-free area.
This series includes red, white, pink and red, lavender, orange, and lilac options.
Grab some in ‘Blushing Lilac’ at Nature Hills Nursery.
Paradise
Paradise™ is a series known for its brightly-colored flowers and a compact, mounding growth habit. And the blossoms won’t quit from spring to fall.
Look for colors like salmon pink, peach, red, orange, lilac, and rose.
Rockapulco
Single impatiens are gorgeous, but doubles like the flowers in the Rockapulco® series are all the more striking.
They look like miniature roses smothering the dark green leaves on a 20-inch-tall plant.
Plants in this series feature coral, purple, rose, white, and classic pink flowers.
Spectra
The Spectra series is made up of plants that have excellent branching and extremely large blossoms, making them an exceptional choice for container growing.
They come in red, magenta, orange, pink, white, and bicolor pink.
Managing Pests and Disease
The New Guinea species is much more sturdy and able to withstand disease and pests than the common species.
Rabbits and deer are certainly adorable from afar, but once they find your flowers, either of these animals can become public enemy number one.
They love impatiens, regardless of the species, and they can mow their way through an entire flower bed in one night.
If you struggle with deer and rabbits, get out the fencing and repellants.
And while they aren’t likely to be a problem, it’s not unheard of for the following to find their way to your plants as well:
Pests
Unlike their wallerina cousins, the hawkeri species is resistant to most pests. It’s really just the red spider mite that you need to worry about.
Spider Mites
Breeders have been working to create mite-resistant plants, but in the meantime, we have to keep an eye out for these annoying creatures.
The main species that will infest impatiens are red or two-spotted spider mites (Tetranychus urticae).
Even though they’re difficult to see, these pests are extremely common, and you’ve probably had them in your garden before even if you didn’t know it.
The pests themselves look like little red, orange, or yellow dots scurrying around on the plant, though you might notice the webbing that they leave behind first.
These mites use their sucking mouthparts to feed on the plant, leaving yellow stippling behind. In large enough numbers, they can overwhelm and kill a plant.
Dealing with them is easy. If you catch them early, just spray off the foliage with water to knock them away. For more tips, read our guide to managing spider mite infestations.
Slugs and Snails
In my experience, herbaceous plants that do well in moist areas tend to be a favorite of slugs and snails, and that’s true here.
Those feet with a stomach (that’s what gastropod means) will steadily work their way through your flowers, leaving them ragged or sometimes missing entirely.
Read our guide to learn some handy methods of snail and slug control.
Whiteflies
If you’ve ever noticed a plant that seems to be covered in flecks of white and tan, or you touched a plant and a bunch of small insects rose up in a tiny white cloud, you’ve probably witnessed a whitefly infestation.
These aren’t true flies, but rather, sapsucking insects that cause yellow stippling, reduced growth, and even dead leaves. They also spread disease.
Read our guide for all the information you need to identify and address a whitefly infestation.
Disease
New Guinea impatiens are more notable for the diseases they don’t typically succumb to rather than the ones they do.
These plants aren’t troubled by downy mildew, which is a disease that has decimated I. walleriana.
Nonetheless, there’s one in particular to be on the lookout for.
Impatiens Necrotic Spot Virus
While it isn’t a widespread problem, impatiens necrotic spot virus (INSV) can be quite damaging.
This virus is spread by insects, which means you really need to do your best to keep western flower thrips (Frankliniella occidentalis) away.
If infected, your plants will show stunted and distorted growth with discoloration on the leaves. You’ll see dark green and black spots, along with similarly colored steaks or rings.
Sadly, there is no known cure. If you’re growing your plants indoors, you can just let them do their thing.
Outdoors, you should probably pull them to avoid spreading the virus to other impatiens in your or your neighbor’s yard.
Best Uses
New Guinea impatiens are perfect bedding plants, and you’ve probably seen them filling in spaces next to walkways or in the front of gardens. They’re also perfect in containers or hanging baskets.
Adaptable enough to live in full sun to full shade, remember they’ll be mostly foliage plants in shady areas.
You also can’t beat them if you want to do some mass planting.
Depending on whether you’re growing your flowers in shade or sun, impatiens play well with astilbe, begonias, coleus, dianthus, ferns, fuchsia, hostas, and sweet alyssum.
Quick Reference Growing Guide
| Plant Type: | Herbaceous tropical perennial | Flower / Foliage Color: | Lavender, lilac, orange, pink, purple, rose, salmon, violet, white/green |
| Native to: | Papua New Guinea | Tolerance: | Shade |
| Hardiness (USDA Zone): | 10-12 | Maintenance: | Low |
| Bloom Time/Season: | Spring, summer (annuals), also some blooms in fall/winter as perennials | Soil Type: | Loose, rich |
| Exposure: | Full sun to part sun | Soil pH: | 5.5-6.5 |
| Time to Maturity: | 12 weeks from seed | Soil Drainage: | Well-draining |
| Spacing: | 18 inches | Attracts: | Bees, butterflies |
| Planting Depth: | Soil surface (seed), same depth as in container (transplants) | Companion Planting: | Astilbe, begonias, coleus, dianthus, ferns, fuchsia, hostas, sweet alyssum |
| Height: | 36 inches | Avoid Planting With: | Cacti or succulents |
| Spread: | 36 inches | Uses: | Bedding, containers, hanging baskets |
| Growth Rate: | Fast | Family: | Balsaminaceae |
| Water Needs: | High | Genus: | Impatiens |
| Common Pests and Diseases: | Spider mites, slugs, snails, whiteflies; impatiens necrotic spot virus | Species: | Hawkeri |
The Flowers You Love, But Tougher
If you ever wished you could grow your favorite bedding plant in the sun, or cried over a bed of dying plants, New Guinea impatiens are going to be a game changer for you.
Which cultivar are you planning to grow in your yard? How are you going to use it? Fill us in on all the details in the comments below.
If you’d like to fill your garden up with some more excellent flowers that are perfect for mass planting, consider visiting some of these guides next:
Kristine Lofgren
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