Some hydrangeas bloom on new growth and should be pruned in late winter or early spring, before the shrub begins active growth. These include several varieties that have become quite popular: Limelight, Quickfire, Burgundy Lace, as well as the classic"snowball" types, such as Annabelle. Nov 19, To renew a hydrangea that you don't regularly cut back, prune out one-third of the stems at the base -- selecting stems evenly across the plant -- each year for three years.
What you want to do is wait until they start leafing out in spring. You'll probably notice some stems are light brown with no signs of life. Prune them back to just above where you see fat, green buds starting to open. Most of these buds should produce flowers.
Immediately after the flowers fade in summer, cut these stems back if you stumpgrind.buzzted Reading Time: 4 mins. Sep 24, Cut back after flowering to the second pair of leaves below the head in order to prevent seed developing.
On established mopheads and lacecaps, cut one or two of the oldest stems at the base to encourage the production of new, vigorous replacement growth. Hydrangea serrata can be pruned in the same way.