House + Home Q&A

Impatiens: To plant or not to plant? Local experts and growers say ‘Go ahead’

Updated: 2013-05-26T00:15:41Z

By ALICE THORSON

The Kansas City Star

Reports of downy mildew, a fungal disease that attacks the popular walleriana species of impatiens, have left many Kansas City area gardeners wondering if it is safe to plant the beloved shade annual. When plants are infected, the leaves turn yellow, and their undersides develop a downy fuzz, hence the name.

Numerous articles have been sounding the alarm, noting that the fast-spreading spores have devastated plants in 35 states and recommending alternatives that are not affected, such as New Guinea impatiens. We asked local experts to weigh in on the topic, and they say the warnings may be premature for gardeners in the Kansas City area.

Dennis Patton, horticulture agent, Johnson County K-State Research and Extension

(Downy mildew) is not anywhere in the Missouri/Kansas area. They did find a sample in a Kansas greenhouse, which was then eradicated, so it never made it out of the greenhouse. There are questions of whether it will spread outdoors in the Kansas City area because our conditions are so different from the areas where this has been reported. I’ve heard Disney World can’t plant impatiens, but our humidity and temperatures are nothing like the East Coast and Florida.

I’m not saying it won’t come to Kansas City. I’m saying we can go ahead and plant impatiens like always until it becomes our problem. When you buy, make sure the plants are healthy. Do proper spacing so they don’t get overly crowded. Planted in shade or light shade, they’ll flower their hearts out, and they thrive as long as they’re well watered. They’re not highly drought tolerant.

The nice thing about annuals is if something does change, we can always switch out the next year. I question the advice to plant New Guinea impatiens (as a substitute) for walleriana. They don’t really like our heavy clay soils. They thrive best in pots unless the soil is heavily amended. New Guinea impatiens are more expensive. I’d hate to see people run out and replace walleriana with New Guinea and then fail.

Mary Werth, horticulturist at Suburban Lawn and Garden

From all the research I’ve done there are no documented cases in Kansas, Missouri or Nebraska for downy mildew. And when impatiens are growing, our climate is not conducive to sustaining downy mildew. At Suburban, we go to great lengths to keep our supply clean of downy mildew. If we have to bring in supply, we go west. We don’t bring supply from out east that could be infected. We’ve done some from seed, but we grow most of them from plugs from Colorado.

We’re fully stocked with impatiens and sold a lot of them over Mother’s Day. If someone has questions, we reassure them that it’s just fine.

And everybody needs to realize that even if our climate was conducive, the disease only attacks walleriana. It does not attack SunPatiens or New Guinea impatiens.

David Trinklein, associate professor, division of plant sciences, University of Missouri-Columbia

The fungus responsible for impatiens downy mildew favors cool, moist conditions. While these conditions are common in spring production greenhouses, they are atypical of a Missouri summer. Additionally, unless the disease is introduced on infected plants, there is no reason to assume it is present in an individual’s garden.

I would not discourage gardeners from planting impatiens but would urge them to obtain their plants from a reputable grower and to make sure they are disease-free before setting them into their gardens.

Lekha Sreedhar, associate professor of horticultural sciences at JCCC

It is a serious problem for greenhouse growers, but for a consumer, it shouldn’t be much of a problem if you buy healthy stock. My students have an annual plant sale here, and they are carrying some impatiens.

I love impatiens. If the plants are healthy when I buy them, I would definitely use them. If you notice the leaves are yellowing and if you look at the underside and see a grayish coloration, it’s better to clean your beds and not plant impatiens for a couple of years.

Matt Archer, president of Soil Service Garden Center

It’s not an issue yet, and it’s very unlikely to happen. If it does we can deal with it later on. As of now there are no reported cases in the Kansas City area or the Kansas area, and we’re inspecting all of our crops as they come in and the growers are doing the same. The growers do have access to fungicide that they are spraying to prevent any outbreaks.

We’ve not cut back on our supply this year, but we did switch suppliers. We used to order from many sources, but every impatiens I’ve carried this season is locally grown, in either Missouri or Kansas.

Once we get past the cool part of the season, the conditions do not favor downy mildew and we all know Kansas City gets pretty hot and dry in the summer months — hopefully not too soon. That may be the reason why we’ve not witnessed downy mildew here. The conditions are not favorable here in the Midwest for it.

We heard that the big outbreak occurred last year with all those storms that traveled up the East Coast. It seemed to spread the disease more quickly than anyone was ready for. It had previously confined itself to the lower southeastern section of the U.S., but the weather pattern spread it pretty quickly.

To reach Alice Thorson, call 816-234-4783 or send email to athorson@kcstar.com.

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