Pruning hydrangeas is essential for healthy growth and vibrant blooms. To do this successfully, it’s crucial to understand the different hydrangea varieties and their flowering cycles. This knowledge allows you to determine precisely when and how to prune these shrubs to maximize their beauty.
The different varieties of hydrangeas
Large-leaved hydrangeas (Hydrangea macrophylla): This category includes ball hydrangeas and lace hydrangeas. They bloom on the previous year’s wood, meaning that the flower buds form in late summer or autumn, to open the following year.
Panicle hydrangeas (Hydrangea paniculata): These hydrangeas bloom on new wood; their buds form in spring only on the new season’s growth. Their flowering period generally extends from late summer to early autumn.
Tree hydrangeas (Hydrangea arborescens): This variety, notably the very popular ‘Annabelle’, also flowers on new wood. The buds appear on the spring growth and the flowers bloom in summer.
Oakleaf hydrangeas (Hydrangea quercifolia): These hydrangeas bloom on the previous year’s wood. Their cone-shaped inflorescences generally open in early to mid-summer.
When should hydrangeas be pruned?
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For large-leaved hydrangeas: Since they bloom on old wood, they should be pruned immediately after flowering, at the end of summer. Pruning too late risks removing the buds that will produce the following year’s flowers.
For panicle hydrangeas: Pruning should be done in late winter or early spring, before new growth begins. Since they bloom on new wood, this pruning will not affect flowering.
For tree hydrangeas: As with panicle hydrangeas, pruning is carried out at the end of winter or the beginning of spring without compromising their summer flowering, because they bloom on new wood.
For oakleaf hydrangeas: These hydrangeas, which bloom on old wood, are also pruned just after they have finished flowering.
How to prune hydrangeas?
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Remove dead or weak stems: Begin by cutting back all dead, damaged, or fragile stems to their base. This step promotes air circulation within the shrub and stimulates vigorous growth.
Deadheading: For varieties that bloom on old wood, prune just below the faded flowers. It’s important not to prune too low, as buds for the next bloom may be located beneath the faded flowers.
Controlling shape and size: To control the volume and shape of your hydrangea, practice selective pruning by removing some branches to maintain the desired form. Avoid over-pruning, especially for hydrangeas that bloom on old wood.
Tools and technique: Use sharp, clean pruning shears to make precise cuts. Cut at a 45-degree angle, just above a healthy bud or at a junction with a secondary branch.
Depending on the hydrangea variety and its flowering pattern, pruning methods and timing vary considerably. Knowing whether a hydrangea blooms on old or new wood allows you to schedule pruning at the right time and use the correct technique. By following these tips, you’ll ensure your hydrangeas remain healthy and produce abundant blooms for many years to come.
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