We have a number of well established peonies that have started to show strange blotches all over their leaves. Can someone advise what it is and how to handle it? Thank you!

It is mildew. When you cut the peony back be sure to discard all of the plant material to decrease the possibility of carryover into next season. You may also have success using products that work on mold or fungus issues.

My foliage trimmings go into bags for city yard waste pickup and subsequent compost. Cleanliness is next to Godliness when it concerns gardens.

magnolialover said:It is mildew. When you cut the peony back be sure to discard all of the plant material to decrease the possibility of carryover into next season. You may also have success using products that work on mold or fungus issues.

That's good to know, tha k you. Can you suggest an appropriate product?

I use Neem Oil and soap blend as a preventative on peonies that tend to have this issue. There are other products out there, your local garden center can help you with what works best for your area.

Also consider the peony's air circulation. If it doesn't dry out after a rain it can lead to this problem.

Thank you SO much!!

I have never had a problem with mildew on peonies before this summer. We have had an very unusual summer with about three times as many over 90 f. days than we usually have with high humidity. As a consequence, one of my peonies started to develop mildew. It was in its early stages. To one gallon of lukewarm water, I mixed one tablespoon of baking soda, one teaspoon of oil (you can use horticultural oil or canola oil) and one teaspoon of regular dishwashing liquid. Shake well. Place portion of mixture in a spray bottle. Then spray the plant. Do this when it is cool and when the plant is not in sun. I did it in the early evening. Repeat in 10 days to 2 weeks, or if it rains.

It worked very well and by the next day, the mildew was looking brownish and "sick". So, I decided to try this mixture on a phlox that always gets mildew. It worked! Neither plant showed any ill effects from the spray.

I am hoping for a summer with more regular temperatures next year

Thanks Valerie for that tip! I have been having a problem with PM on phlox that is really unsightly and ruin the blooms. Next year, I will start spraying them every two weeks with this mixture when they start to show buds.

With regards to peonies with powdery mildew at this time of year, I would just start pruning them off. They are starting to go dormant anyway. I have cut off foliage in August and have not seen a decrease in blooms the following year. Though I do apply a tbsp of bulb fertilizer to these in early spring.

I only had it on one plant (newly planted this year). The spray stopped it dead in its tracks. Mind you, it was in its very early stages when I tackled it. All my other established ones are green and healthy, even though it has been so hot and humid. Thank goodness for peonies and daylilies being fairly drought resistant!

I have two phlox that are fairly mildew free, but this old cultivar is not. I believe the old one is Blue Boy.

Thanks for the tip about pruning them back. Does it make a difference that I am north of you, so my plants start growing later?