My oak leaf hydrangea is not blooming. Lots of leaves, plant is healthy other than a few bug. It is in a sunny place in Richmond Hill, Ontario.
Thank you for contacting Toronto Master Gardeners.
From the photo, it appears that the hydrangea has been pruned at some point. Oakleaf hydrangeas flower on old wood carried over from the year before. So, if the shrub was pruned in late summer, the flower buds for the following year were removed. Prune these shrubs, if necessary, immediately after flowering.
In the photo, the leaves appear brown at the edges, which suggests the plant may not be receiving sufficient water, another possible reason for failing to bloom.
Other possible reasons for no flowers:
- Winter injury has occurred to the flower buds of a hydrangea that blooms on old wood. In Toronto, we had some very hot days near the end of May, followed by snow! This may have damaged the buds. You should protect the plant on spring nights when frost or freeze threatens.
- Hungry deer have eaten the branches bearing flower buds.
- The hydrangea is not receiving enough sun. (Hydrangeas typically need at least four hours of sun a day, and some varieties need even more.)
- The hydrangea is receiving too much sun. (Yellowing or browning of leaf edges and tips is another sign of this problem.)
- Excessive application of nitrogen fertilizer has encouraged leaf growth over flower production.
I hope this helps you determine how to make your hydrangea bloom.
September 19, 2021