Lacecap and mophead hydrangeas are best pruned in spring. This prevents them becoming woody and congested, and channels their energy into producing strong growth and large blooms.
Hydrangeas are an exception to the rule that says shrubs that produce their flowers on the previous season’s growth should be pruned after flowering. The structure of hydrangea stems means it’s best to leave cutting back until spring. This is because the stems are cork-like, rather than woody, and hold enough moisture inside them during winter for this to freeze in frosty weather. If they are pruned in autumn, after flowering, the buds can freeze, killing the stems and their buds. Make sure you’re using the right pruning tools, in our guide to the best pruning tools.
Leaving the old flowers on the plant over winter, until the worst frosts are over, will help protect the stems and their new buds. Once the sap starts to rise in spring, these buds will open and many should go on to carry blooms the following year.
Remove last year’s flowerheads
Remove old flowerheads just above a pair of buds. Hydrangea buds can be easily knocked off, so cut carefully using the tips of your secateurs. If the plant has many stems, cut at an angle between the buds to remove one of the pair. This will direct growth into one shoot rather than two, preventing the plant from becoming congested.
Cut out thin, weak stems
Cut out any thin, weak stems around the base of the plant and remove one or two of the largest, oldest stems from as low down as possible to promote new shoots from the base. These will grow over the next few years and carry blooms in the future.
Discover how to prune spring-flowering plants.
Pruning climbing hydrangeas
Climbing hydrangeas such as Hydrangea anomola subsp. petiolaris should not be pruned until after they have flowered, in summer.