This is the first of several posts on pruning. I was asked again last week about pruning hydrangeas. There is much confusion about when and how to prune.

First, know whether the species you are pruning blooms on old wood or new wood. The easiest way to know this is by noting bloom time. If the plant blooms before July (H macrophylla, serrata, quercifolia), it blooms on old wood. If it blooms later in the summer (H panniculata) it is blooming on new wood. The best time to prune any flowering shrub in order to maximize next year’s blooms, is just after blooming.

Prune new-wood blooming hydrangeas either all the way to the ground, back by a third, or remove 1/3 of oldest canes and tip prune (whichever you find least unattractive-I have a difficult time finding any redeeming aesthetic quality in this shrub during the winter months). The idea is to have a lot of new growth since the old wood is not very productive for flowering. This pruning can be done from fall through spring before new growth begins.

Prune old-wood blooming hydrangeas by removing 1/3 of oldest canes (these are generally the scraggly, crossing canes that are unattractive) all the way to the ground and then pruning the tops back to 1/2 (flower buds are formed all along the stem but do not develop unless the terminal is removed.

Next week I’ll post on pruning formal hedges.