Why are knockout rose blossoms turning brown before maturing? My 3 yr old knockout roses were beautiful the first year they were planted. Next 2 years, blossoms developed and appeared to bloom fine the first time in the spring, but later the next blossoms turned brown, dying before the blossom matures and sheds. Plant looks healthy, responding well to pruning each year. What's going on with the blossoms?
Knockout Rose Blossoms Turning Brown
It surely does sound like you have some Thrips getting after your rosebushes. I would give them all a spraying with some Bayer Advanced Complete Insecticide. Then in a couple days give them all a treatment of Bayer Tree & Shrub granules per the label instructions for shrubs/ornamentals, work it into the soils lightly and water in well. This product has both a feed in it for the roses to help them gain strength but also a systemic insecticide that moves through the rosebushes natural juices to get after those hard to kill and find insects. Here is an article on thrips for you to check out as well: https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-thrips.htm