Annuals Houseplants

How Can I Overwinter a New Guinea Impatiens?

Pink New Guinea Impatiens
New Guinea impatiens. Photo: hecos, depositphotos

Question:

Every year, I bring in a New Guinea impatiens at the end of September. And every year, after about 2 weeks, the leaves fall off or dry up and only a stub remains. A few weeks back, you recommended in one of your articles that it’s best to bring tender plants in early, before they undergo any cold. Does that mean that part of the problem is that I start doing it too late? Or should I just abandon the idea?

Frank,
Grand Falls, Minnesota

Answer:

You live in an area well known for its cold autumn weather. I figure you must live in hardiness zone 3. That’s a zone where frost is not unknown even in August. So, logically, yes. You’d certainly be a prime candidate for “early entry”. Absolutely, you’d do much better to bring your plant in before it gets too cold.

Orange New Guinea Impatiens
While it may look spectacular in a flowerbed or an outdoor container, New Guinea impatiens don’t make good indoor plants. Photo: claudiodivizia, depositphotos

Now, add to that the fact that this impatiens is known to be “difficult” to overwinter in general: it’s not just you who has problems with it. Few gardeners manage to keep it growing over the winter for very long. It’s generally easier to buy new cutting-grown specimens from a commercial greenhouse in the spring, when it’s sold with the other “annuals” that will decorate our gardens through the summer. And nurserymen certainly aren’t unhappy that their customers find the New Guinea impatiens difficult to keep. That ensures a great boost in sales in the spring!

But that said, this impatiens is still not a “true annual”, a plant that goes through its entire life cycle, from seed to bloom to seed, in one year. Instead, it’s a perennial, but a tropical one, though: hardiness zones 10 to 12.

Its Origins

Pale pink New Guinea impatiens.
A primitive form of New Guinea impatiens, very close to the wild species. One of the spurs can be seen very clearly. Photo: Forest & Kim Starr, Wikimedia Commons

New Guinea impatiens is native, as its name suggests, to New Guinea, but also to the Solomon Islands and other islands in Oceania. The original species, Impatiens hawkeri, is highly variable. So much so that it was originally grouped into 14 different species (I. schlechteri, I. mooreana, etc.) before taxonomists decided that it was just one very elastic species that fit quite nicely under just the name I. hawkeri. The large flowers come in varying shades of pink, purple, white, orange, and red, as well as various bicolors. All flowers have a long spur filled with nectar, a reward for pollinators… but often hidden from view at the back of the flower.

New Guinea impatiens with colorful foliage.
Foliage color also varies. Photo: drburhan, depositphotos

The toothed leaves are 3 times larger than those of its more popular cousin, the garden impatiens (I. wallerana), of African origin, the famous shade impatiens (the New Guinea impatiens is not quite as shade resistant). New Guinea impatiens leaves also come in different colors—green, purple, variegated with white, yellow, pink or red marks, etc.—even in its natural state. In cultivation, of course, hybridizers developed new varieties that are even more colorful and variable than the wild forms… and better garden plants, too.

The plant forms a rounded dome of thick, succulent stems, reaching up to 2 feet (60 cm) in height and diameter, although modern varieties are often more compact: 8–20 inches (20–50 cm) in height and 10–16 inches (25–40 cm) in diameter.

Unlike woody tropical plants (shrubs and climbers) such as pelargoniums, fuchsias, hibiscus and mandevillas, where you can sometimes force the plant into dormancy by cutting back on watering and keeping it cool during the winter, New Guinea impatiens is not drought tolerant. If you let it dry out, it simply dies! So, “forced dormancy” is not a method you can use in looking for a way to overwinter your plant.

Start Early When Bringing in a New Guinea impatiens

New Guinea impatiens with few flowers, after a bit of fall cold.
New Guinea impatiens in the fall when it’s time to bring them in. Photo: www.uaex.uada.edu

To overwinter a New Guinea impatiens, start very early in the fall, before the nights are cold. When they near 55°F (12°C), it’s time to get moving. That could be as early as the end of August in colder areas. If you keep houseplants outdoors for the summer, this would be the right time to bring them in as well.

Bring in either stem cuttings (root them under high humidity, such as under a dome or in a mini-greenhouse) or cut back plants you dig out of the garden back by two thirds. Water them well and bring them indoors into a warm spot.

Mind you, these are mountain plants: they don’t need hot temperatures. Fairly cool indoor temperatures, 5 to 10°F (10 to 20°C), would be perfect. As spring approaches, raise that a bit to simulate the coming of summer conditions.

Maintain high humidity (60% minimum) and fairly intense lighting. Ideally, you’d give them full sun in the morning and partial shade in the afternoon. Artificial lighting (using fluorescent lamps or LEDs) may well be necessary. Don’t expect much bloom in fall and winter, those aren’t their main flowering seasons. Instead, they’ll start to bloom more and more abundantly in spring and summer.

This is a tricky plant to water indoors. It rots if overwatered, but wilts very quickly—you’d almost swear it had melted!—if not watered enough. The secret is to wait until the soil is dry to the touch, then water thoroughly with lukewarm water.

Pest Patrol

A weakened plant attracts pests and a New Guinea impatiens is always stressed in our homes. Shower the foliage regularly to control spider mites and thrips.

As Spring Approaches

Around March, you can take cuttings under high humidity (place them under a dome or inside a clear plastic bag) to increase the number of plants in time for the upcoming gardening season.

Variegated New Guinea impatiens, orange flowers.
New Guinea Impatiens ‘Celebrette Light Coral’. Photo: Karl Gercens, flickr.com

Later in the spring, when outdoor temperatures warm up, you can start to acclimatize your New Guinea impatiens back to summer conditions for a 2nd flowering season. The plant should be in flower again before the end of April!

Good gardening!

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, laidbackgardener.blog will continue its mission of demystifying gardening and making it more accessible to all.

5 comments on “How Can I Overwinter a New Guinea Impatiens?

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  3. I’ve always found it easier to take cuttings and root them indoors on a windowsill.

  4. Bill Russell

    Please note that “Fairly cool indoor temperatures, 5 to 10°F (10 to 20°C)” does not make sense! I am sure you do not mean 5 to 10°F, which would be below freezing. If you mean 10 to 20°C, that would be 50 to 68°F.

  5. This was definitely a ‘learning’ post. Thank you for taking the time to explain. I will continue to buy mine in the spring and help the plant industry prosper.

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