A: I’ve received this question a lot this summer and am victim to the same disappointment. Many macrophylla, or ‘mophead’, hydrangeas failed to produce blooms this year, though the leaves look great!
The two freezes many of us experienced back in March are most likely to blame. Let Mother Nature bear the burden of responsibility for this one! But, this is a good opportunity to remind gardeners about proper pruning for hydrangeas. Just always remember “prune after bloom”. If mopheads are pruned back much later than August or September, the plant may have fewer blooms on it in late spring / early summer. Panicle hydrangeas are blooming prolifically right now. Since they bloom on ‘new’ wood, referring to the new growth put out in the spring, I’ve just always cut mine way back around St. Patrick’s Day! That means having to look at the bare branches through the winter, but I don’t mind.
Another common question about hydrangeas right now is about Cercospora Leaf Spot showing up on the leaves. With warm days and cooler nights, coupled with high humidity, this is common. Fungal spores populate in these conditions and with overhead irrigation or rainfall, they can quickly be spread to other leaves. Infected leaves that have fallen from the shrub can act as a source for spores of Cercospora leaf spot, so it is important to remove any diseased leaves that have fallen from the ground below. And if it’s in its early stages, hand picking highly infected leaves from of the plant can slow the spread.