The pruning mysteries of Hydrangeas solved!

Does it bloom on new wood or old wood?

Well, here in the Chicago area it seems that the 4 popular types are the
Annabelle, Bigleaf hydrangea, and panicle hydrangea.

So, the Annabelle or Hydrangea arborescens form buds on new wood and
should be pruned back in the spring to about 18-24”. This ensures that they don’t
get to leggy.Another reason to wait until spring is to provide winter interest.

Bigleaf, Hydrangea macrophylla tend to be unreliable bloomers here in the
Chicago area due to the cold winters. And, they form their buds on old wood and should be pruned after they bloom.
So covering the plant with mulch in early November may help decrease bud die back. Then
when spring comes cut back any dead branches.

Panicle Hydrangea, Hydrangea paniculata only needs to be deadhead as it forms buds on old wood and if there are crossing or spindly branches prune those as well.