Hydrangea leaf spots

Asked October 5, 2017, 6:49 PM EDT

I have Hydrangea macrophylla 'Blue Wave' and 'Lilacina' shrubs. They are about 20 years old; about 6 feet in height and 8 feet in diameter. They are in shade to partial shade most of the day but do receive some direct sun late in the afternoon. The exposure is northwest. They do not receive supplemental water unless wilting is evident. They have bloomed very well every summer. Flowers are usually large and numerous. The flower color is usually between blue and pink which would indicate, I think, a neutral soil pH. However, this summer the leaves receiving the most sun have developed brown spots and the flowers were smaller and not as numerous as in previous years. Leaves continuously shaded all day did not exhibit spotting. I also noticed that leaves on shoots coming up from the bases of the plants look chlorotic. Pictures are attached. How should this problem be addressed (culture, pruning, chemical)?

Baltimore County Maryland

1 Response

Your plant does look unusually stressed. Did it look better before the drought of the last month?
It is not usual, especially in wet years for hydrangea to have fungal and bacterial leaf spots, but they are seldom of concern.
We also had a late frost that zapped a good deal of flower buds that had already broken dormancy.
We suggest trimming it way back next spring (you will forgo flowers next year) to get rid of the spindly, weak growth.
A soil test would not be a bad idea.
Here is how to get that done: https://extension.umd.edu/hgic/soils/soil-testing

You also might be interested in some programming that nearby Ladew Gardens has. Look them up. There is a lady there who gives classes in hydrangeas and their care.