Hydrangea: Prune old wood or new wood?

Before you even approach pruning your hydrangea, ask yourself what type of hydrangea you have. If you don’t remember, maybe give the nursery or greenhouse a call or ask an Extension agent. Sometimes, the plant you purchased is marked on the receipt. But don’t begin any pruning unless you have a positive ID for your hydrangea. If you do decide to just prune, you may destroy this year’s flowers.

In understanding how to prune hydrangea, we need to know whether the type of hydrangea you have grows flowers on old wood or new wood. Hydrangeas create flowers on old wood and start producing flowers shortly after this season’s flowers bloomed. Think of it this way. These hydrangeas have current flowers and future flowers both on the old wood.

What type of hydrangeas produce flowers on old wood? Hydrangea macrophylla, Bigleaf Hydrangea, Hydrangea serrata, Cascade Hydrangea™, Mountain Hydrangea, Hydrangea petiolaris and Oakleaf Hydrangea. The best way to prune these is not to prune these at all. Just let them grow because their stems produce both this current season’s flowers and next season’s flower production starting immediately after the current season’s bloom. If you prune, you will not have flowers for a year. Naturally, prune out dead stems.

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