Q: How do I prune hydrangeas?
A: Pruning requirements depend on whether the plant blooms on new or old wood. Hydrangea arborescens cultivars, such as ‘Annabelle’ and Incrediball, bloom on new growth, so in early spring cut back the stems to a pair of strong buds at a height of 30 to 45 centimetres. In a very hard winter, they might die back to the ground but should re-sprout from the base.
H. paniculata ‘Grandiflora’ (syn. PeeGee) can be treated the same way or given just a tidy up.
Bigleaf or mophead and lacecap hydrangeas (H. macrophylla cvs.) bloom on previous year’s growth. All they need in spring is removal of spindly, twiggy growth, spent flowerheads, any winter dieback and a few of the stems that are more than three years old (to rejuvenate the shrub). Oakleaf hydrangeas (H. quercifolia and cvs.) require only the removal of dead or damaged branches, and deadheading after flowering.