More severe damage may show immediately after the storm as tears or irregular holes, or shredded leaves and flower clusters. Minor damage may not show immediately, but may appear days or weeks later as small whitish scars or spots on the leaves. Both of these diseases can be spread by splashing water and diseased plant materials including fallen leaves.ĭamage to plants depends on size of the hailstones and intensity of the storm. Anthracnose may cause large, round or angular blotches which can appear all over the plant, including the flower heads. Cercospora leaf spot typically causes small necrotic spots beginning on the lower leaves and progressing upward on the plant. Leaf spot diseases are usually noticed in midsummer to early fall. Spotting may range from mild to severe and severely affected leaves may turn yellow and drop from the plant. These may be surrounded by a reddish or purple halo.
Symptoms may include brown, black, or gray spots or angular blotches. Several fungal diseases cause spotting of leaves on hydrangeas. Plants which are placed in very shady locations may not bloom as profusely as those that receive more light. Freezing temperatures early in the fall before the plant is completely dormant, late-season spring frosts, and very cold winter temperatures can damage or kill developing flower buds. Bigleaf hydrangeas may also fail to bloom due to environmental conditions. arborescens) hydrangeas flower on current-season growth, so heavy summer pruning of these species can reduce flowering.
If these stems are removed, new growth may fail to produce flowers that season. quercifolia) hydrangeas produce their flowers on the previous year's growth. Both bigleaf (Hydrangea macrophylla) and oakleaf (H. Improper pruning is the most common reason hydrangeas fail to bloom.
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