HOW DOES YOUR GARDEN GROW? — Many gardeners prefer impatiens for shade, but a disease called downy mildew is killing that plant. Impatiens might perform well in your garden through August, or it might not. Weather plays a big role, said an expert from Cornell University. Photo of healthy impatiens courtesy of Margery Daughtrey.
HAMBURG — Last year, I told my readers that impatiens, everybody’s favorite shade flower was doomed. A disease called downy mildew is killing impatiens. I said that, if downy mildew is in your garden and gets on your impatiens, those plants will die.
After talking to Margery Daughtrey, senior extension associate with Cornell University who co-wrote a fact sheet on how downy mildew affects impatiens, I think the message this year might be slightly more optimistic.
Impatiens might do OK in your garden, this year. It depends a lot on this summer’s weather and how you define “OK.”
Gardeners who planted impatiens in Western New York last year, and encountered downy mildew, did end up with dead plants. The disease destroys the plant. The plant could be fine, and then the leaves would turn yellow and quickly drop; the flowers, and even the stems, then dropped.
Many gardeners were still satisfied, because the impatiens lasted through July and into August. Having pretty flowers for the shade in the middle of summer is enough for them, and if the plants die in August, that is OK. A frost might kill the plants at the beginning of September, anyway.
There seem to be a couple of explanations as to why the impatiens lasted that long. One reason is that growers applied fungicide to the plants, to protect against downy mildew in the greenhouse. That fungicide may have protected the plants for a month or more outside the greenhouse, Daughtrey said.
The other thing that worked in favor of impatiens last year was the weather. Wet weather and cool temperatures help the disease thrive and spread. It was wet here in early June, but the fungicide that the growers applied may have protected the plants, at that point. Then we got hot, dry weather, which may have discouraged the disease.
“How impatiens performs this year depends, to a huge extent, on the weather,” Daughtrey said. No one can predict now what our weather will be like, this summer. We may have years in which impatiens do well in our gardens, and years in which they do not.
The cold winter we had this year did not kill the disease.
If you want to try impatiens this year, go ahead, but there are still no guarantees, with these plants.
“Don’t put all your eggs into the impatiens basket,” Daughtrey said. “If you want a pretty garden, bring in other plants. You want a mixture of plants, not a monoculture.”
If your impatiens does get downy mildew, there is nothing you can buy or make, to treat it. Nothing.
There are a few steps you can take, to encourage healthy impatiens in your yard for as long as possible.
Buy healthy plants. Look at the underside of the leaves. If the underside of the leaf looks white and sugary or white and cottony, that is a sign of downy mildew. Do not buy this plant. If you see purple splotches, don’t worry about it; that is normal.
Be careful how you water. Since downy mildew thrives in a cool, moist environment, do not water at night. Instead, water in the morning, so the leaves have time to dry off, before the temperatures cool down.
Try planting impatiens in containers and setting them on a porch or other area where a roof shields them from rain. When you water plants in containers, you tend to water the soil rather than spray the leaves, which can also help. Impatiens located in a hanging basket may benefit from better air circulation.
If you want to try impatiens this summer, you may get good performance from them into August, but there are no guarantees. Connie Oswald Stofko is the publisher of Buffalo-NiagaraGardening.com
, the online gardening magazine for Western New York. Email