By Pat Curran, Horticulture Educator, Tompkins County Cornell Cooperative Extension, (Published September 2010)
Question: Why didn't my hydrangeas bloom this year?
Answer: There could be several different reasons for hydrangeas not blooming. Some reasons differ, depending on what kind of hydrangea it is, since we can grow 5 different species of hydrangeas.
But let's talk about the general reasons first. The bush may not be mature enough to bloom. Most woody plants do not bloom when they are very young. A newly planted bush may bloom the first year if it set flower buds while it was confined to a pot, and then not bloom again for a year or two as it settles into the soil in its new location. Instead it is busy growing new roots and branches, instead of flower buds. When it does finally resume blooming, there will be many more flowers because the bush has indeed "bushed" out!
A sadder reason is that deer may have eaten the flower buds. Look for rough torn stem ends where deer, lacking incisors, have torn the buds off. Also, hydrangeas are all moisture-loving plants so if drought occurs at the wrong time, flowering may not occur.
Sometimes, gardeners have pruned the hydrangeas at the wrong time. This is where identifying the species gets very important. Two species we grow bloom on new wood (new growth of the current growing season). These are the panicle hydrangea, Hydrangea paniculata, also called the PG hydrangea, often seen heavily planted in cemeteries; and the native smooth hydrangea, Hydrangea arborescens, usually seen with white mophead flowers, and often sold as the cultivar 'Annabelle.' These 2 species can be pruned in early spring, and the new growth will flower later in the summer.
However, our other 3 species of hydrangeas bloom on old wood (growth from the previous growing season). These are the climbing hydrangea, Hydrangea anomala petiolaris, a wonderful vine for partial shade; the native oakleaf hydrangea, Hydrangea quercifolia, with great red or maroon fall foliage color; and most varieties of the very popular blue or pink bigleaf hydrangea, Hydrangea macrophylla. If these species are pruned in the fall or early spring, the flower buds will probably be cut off. Instead, pruning should be done right after blooming, before the new flower buds form.
In the last several years, several new varieties of the bigleaf hydrangea have been introduced. Called "remontant," they bloom on new wood as well as old wood. If one grows these varieties, another reason for lack of bloom can be avoided. Older varieties of Hydrangea macrophylla that are not remontant have flower buds that often do not survive our winter temperatures. Gardeners who live in the city or near the lake, where it doesn't get as cold, often have success with these varieties, however. Out in the country, a winter with deep snow cover may also protect the flower buds enough from the cold.
Last updated June 23, 2015