Pruning Big Leaf Hydrangeas (macrophylla)
The timing of pruning is very important on this plant. They bloom on old wood, so pruning is done in summer before next year’s flowers start to set. You may prune as the plant is flowering. Weak and poorly formed branches should be removed and on well-established plants, some good branches could also be removed to force new growth that will have flowers next year. Don’t prune after July! Flower bud hardiness is a concern, sometimes because it is too cold, other times because the plant breaks dormancy too early.