Most hydrangea varieties – hydrangea pinky winky, quick fire hydrangea, nikko blue hydrangea, vanilla strawberry hydrangea, little lime hydrangea, etc. – are easy to tend provided that you water and fertilize them properly. But in some cases, your hydrangea shrubs simply refuse to bloom.
There are three possibilities that can account for the absence of blooms among the different hydrangea species. The three factors that result to the lack of flowering are too much shade, improper pruning, and weather-related damage to the buds. Weather-related damage applies in particular to the bigleaf hydrangea.
Shade is beneficial to hydrangeas, but too much of it will discourage flowering. This is very true in the case of the panicle hydrangea, because it needs full sun to thrive and bloom properly. If there are a lot of trees growing around and shading your hydrangeas from the sun, then they can exacerbate the issue of the lack of flowering. You may want to transplant the hydrangeas in locations where they get sunlight.
Improper pruning can also deter flowering in hydrangeas. Since bigleaf hydrangeas and oakleaf hydrangeas bloom from the previous year’s growth, then their potential flowers buds will be excised if the stems are pruned during the fall, winter, or spring. In the case of the panicle and the smooth hydrangea, they flower on this year’s growth, meaning if you prune them early in the summer, it will eliminate or reduce their flowering for that specific year.
The bigleaf hydrangea is the species which is readily affected by weather conditions. In fact, the most common reason for lack of blooming for the bigleaf hydrangea is inclement weather. Most of the H. macrophylla cultivars bloom mainly from previous year’s growth. Thus, the weather conditions which damage the upper parts of the plant will significantly reduce flowering. Potential damaging weather conditions for bigleaf hydrangeas include early fall freezes which happen before the shrub is completely dormant, very low winter temperatures, and late spring freezes which happen after the shrub has broken dormancy.
The good thing is that bigleaf hydrangea responds fast to warm temperatures during late winter and early spring by breaking dormancy and producing new leaves. But these bouts of warm weather are usually followed by periods in which the temperatures reach well below the freezing point. The severity of the damage to the bigleaf hydrangeas caused by these freezes depends on the number of the buds that had broken dormancy. If a significant portion of the buds on the stem were growing, then the whole branch may die.