I have 5 Hydrangea plants that don't look very happy. I planted them this spring with transplant fertilizer. And then I added a flower fertilizer earlier this summer. They were looking good until about 6-8wks ago and then they started looking really unhealthy. See photos attached. I labeled each photo with the problem I see. - What is causing the yellowing leaves? - What is causing the leaves to look like they are burnt? Too much sun? - One plant looks like there is a lot of mold on the leaves. I cut some of the leaves off to get rid of it but I don't think that helped. This plant is in the shade most of the day. - Why are the flower blooms smaller? When they first started blooming they were big and bright and full of good color. Now the pedals of the flowers look green, Any help or advice would be great!! I just started gardening this spring and it's not as easy as I thought! Thanks!
Hood River County Oregon
Thank you for your question. The leaf tissue that is black/brown is sun-scorched; the tissue dies, and the whole leaf turns yellow and dies. The leaves that are just yellow are probably in need of fertilizer, especially nitrogen. The mold is powdery mildew, which won’t hurt the plant long-term, but which you can control with an organic spray like Neem oil. Flowers just naturally fade over the summer. One plant can have many sizes of flowers. Here is a general OSU Extension article on them: https://extension.oregonstate.edu/gardening/flowers-shrubs-trees/general-care-hydrangeas Hope this is helpful. Good luck!