If you have noticed a white or grayish powder on your peonies (or any of your other plants) this summer, it’s probably powdering mildew.  And don’t worry! Your peonies are not the only ones; we have seen powdery mildew on peonies (including mine) all over town. Powdery mildew is a type of fungus that can occur on any type of plant. Plants that are particularly susceptible to powdery mildew are salvia, zucchini, cucumbers, zinnias, bee balm, tall phlox, and columbine. Powdery mildew is usually caused by moderate temperatures, shade, excess moisture and humid conditions- so there is not much we can do at this point to prevent it, however, we can treat it. The weather here in Northern Colorado in the spring was very odd- we got a lot of moisture so it’s no shock that powdery mildew is showing up all over the place.

The best way to get rid of powdery mildew is to purchase neem oil from your local nursery and spray your plants down once a week.  We buy the concentrated neem oil and mix it in a sprayer and DRENCH the plants from top to bottom. The most important thing to note about this method is that you have to spray when its not hot and sunny out or your plants might burn.  The best time to go spray is around dusk when you can still see what you’re doing but the sun isn’t really up. You can also use horticultural soap or find your own mixture online, but in my opinion, neem oil is superior.

Powdery mildew is nothing to panic about as it won’t kill your otherwise healthy plants but it is important to treat.  If you have any questions about powdery mildew or how to treat it, feel free to contact me!