I live in SW Michigan. Have always had great luck w/Coneflowers, but this year all 3 (different varieties) are displaying the same problem. The buds turn brown and do not open up! My purple and orange coneflower plants managed to produce blooms initially but are now doing the same thing that my yellow one is. Some appear to have partially developed a petal or two but then just seem to halt and turn brown. Others are just completely brown over. No change in my watering habits, has been very humid here this summer and a bit dry over the past few weeks. I usually water if things tend to get super dry. The foliage looks fine to me. These have always been nearly maintenance free and easy to grow. . . any thoughts on what it might be?
Coneflower Buds Browning Not Blooming
Certified GKH Gardening Expert
They may be suffering from an infestation of Eriophyid mites, which live and feed on the insides of flower buds. Damage can be recognized by stunted growth and distorted flowers. Simply remove affected plants and hopefully, this will take care of the issue.
Another possibility is aster yellows disease. On coneflowers, the most typical symptom is replacement of flowers by tufts of small, green, deformed leaves. No treatment is available to save a plant infected with aster yellows. Aster yellows is best managed by removing infected plants from the garden to minimize spread.