Q: I love hydrangeas. I prune and fertilize them but some simply refuse to bloom. What am I doing wrong?
Some hydrangeas can be pruned hard and will bloom reliably every year. Those include the popular peegee hydrangea (Hydrangea paniculata ‘Grandiflora’) and hills-of-snow (H. arborescens ‘Annabelle’). Both have large white flowers, and there are new pink-hued peegees as well.
However, the popular mophead hydrangeas (Hydrangea macrophylla), with their familiar pink and blue blossoms, must be pruned carefully in order to ensure regular blooms. They bloom on the previous season’s wood, so a hard pruning will result in foliage but no flowers. Prune them in the late winter or early spring before they leaf out.
Eliminate old wood to the ground and cut out excessive vegetative growth. But keep the overall shape of the hydrangea by leaving young budded stems. Rounded flower buds should be visible at this time; prune above them. Newer cultivars have been bred to bloom on old and new wood – giving them a longer bloom period. If you have a tendency to prune hard, these plants will still bloom later in the summer on the new growth.