One of the critical factors for successful hydrangea bloom is when and how to prune. The key factor is whether the plant blooms on new or old wood. Do the blooms develop on this season’s new growth or last year’s mature stalks? It is always best to choose a plant that fits the space it will occupy. That way, pruning can be kept to a minimum and done only for the well-being of the plant and to promote vigorous flowering.

There are five types of hydrangeas, which fall into two pruning groups.

One group of hydrangeas bloom on old wood. These plants produce flower buds on stems from August through October for the following summer’s blooms. If these stems are pruned in the fall, winter, or spring, the bloom buds will be removed, and there will be little or no bloom the following summer. Types in this group are:

• Hydrangea macrophylla (mophead and lacecap) Endless Summer, Let’s Dance, Cityline and others. Some newer varieties bloom on new and old wood. The color of the color of the blooms can be affected by soil pH. Pink blooms when the soil is neutral to alkaline and blue when it’s more acidic.
• Hydrangea quercifolia (Oakleaf) Alice, Munchkin, Sikes Dwarf, Snow Queen, this wood is generally more cold-hardy than the wood from macrophylla varieties.
• Hydrangea serrata (Mountain) Tuff Stuff Series and a few other varieties. These are more-cold hardy than macrophylla but still subject to winter dieback. The majority of varieties are lacecap blooms. These are the type that the color of the blooms can be affected by soil pH. Pink blooms when the soil is neutral to alkaline and blue when it’s more acidic.
• Hydrangea anomala petiolaris (climbing hydrangea)

The other group of hydrangeas bloom on new wood. These plants produce flower buds in the current season, beginning about a month or two before they bloom. Therefore, they can be pruned any time after they bloom and up until they begin producing flower buds. Types in this group are:

• Hydrangea arborescens (smooth hydrangea) Annabelle type;
• Hydrangea paniculata (Summer hydrangea) Limelight type;
• The everblooming varieties of Hydrangea macrophylla also belong to group that blooms on new wood, and includes Endless Summer Series and Let’s Dance Series. The flowers on new wood appear late in the summer after the new growth has matured.

If in doubt, only prune off old flower heads and leave the rest until spring. Once June arrives, you’re safe to prune off any stems that have not produced leaves.

Watch our video for more information.