By Joan Nieman-Agapas, Master Gardener, SCMG
To prune or not to prune?
That is the question.
Before you proceed with the secateurs, you must know WHAT type of plant you have.
Hydrangeas belong to a family, and like all siblings in a family, each has its own unique characteristics & hence specific needs.
The members of this family include:
Hydrangea macrophylla (bigleaf/mophead/lacecap)
Hydrangea paniculata (panicle/peegee)
Hydrangea arborescens (smooth/Annabelle)
Hydrangea petiolaris (climbing)
Hydrangea serrata (mountain)
Hydrangea quercifolia (oakleaf)
Once you know your plant type (you kept the tag – right?) you can proceed. Very young plants ie less than five years old, do not need pruning, except to remove dead or damaged stems & spend blooms.
Both panicle & smooth varieties bloom on ‘new wood’.
The remainder: bigleaf, climbing, mountain & oakleaf bloom on ‘old wood’.
What do these terms mean?
‘New wood’ is the growth produced in the current growing season
‘Old wood’ are stems produced in the previous (last year’s) growing season.
If your hydrangea is smooth/Annabelle which blooms on new wood, prune in the spring before leaves emerge. Cut plants back to 15–30 cm (6-12 inches). This will encourage new growth, together with providing a framework to support the flowers.
If your hydrangea is panicle (peegee), again prune in the spring before leaves emerge. Just remove the flowering heads above a strong bud. Prune for shape by removing dead, damaged or crossed stems.
If your hydrangea is one of the other four, which bloom on old wood – do not prune!! Doing so, will remove the flower buds which formed during the previous summer. Protect from harsh weather & wandering wildlife which may eat the flower buds.
Remember, less is more. Hydrangeas do not strictly require regular pruning. Properly sited, they will grow & flower well & with nothing more required than removing spent flowers & any damaged/dead wood each early spring.
Lastly, when pruning, ensure your equipment is sharp and clean.