Deciding whether to cut back hydrangeas in the spring depends entirely on the specific variety you are growing. Pruning at the wrong time is the most common reason a hydrangea fails to produce flowers. Understanding the fundamental difference in how various types of hydrangeas set their flower buds is the first step toward ensuring a beautiful summer bloom.
The Critical Difference: Old Wood vs. New Wood
Hydrangeas are categorized into two major groups based on the age of the wood that produces their flowers. This distinction determines the ideal time for any pruning.
The “old wood” group develops its flower buds on the previous year’s growth, typically in late summer or early fall. Examples include Bigleaf Hydrangeas (Hydrangea macrophylla), which are the classic Mopheads and Lacecaps, and Oakleaf Hydrangeas (Hydrangea quercifolia). If you remove these overwintering stems in the spring, you are cutting away the very buds that would have opened later that year.
The “new wood” group forms its flower buds on the growth produced during the current season, developing after the plant begins growing in spring. This group includes Smooth Hydrangeas (Hydrangea arborescens), such as ‘Annabelle,’ and Panicle Hydrangeas (Hydrangea paniculata), like ‘Limelight’ and ‘Quick Fire’. New wood bloomers are much more forgiving of spring pruning because their flowers are generated on the fresh growth that emerges after the cut.
Spring Pruning Rules for New Wood Bloomers
For hydrangeas that bloom on new wood, spring is the time for a thorough cutback. Pruning these varieties in late winter or early spring, before new growth starts, encourages stronger stems and more prolific flowering. This practice directs the plant’s energy into generating robust new shoots, which will support the large flower heads later in the season.
Cut back the previous year’s growth by about one-third to two-thirds of its total height. Make the cut just above a pair of healthy, outward-facing buds on the cane. For established, overgrown shrubs, a more aggressive rejuvenation pruning can be performed by cutting all stems down to about 12 to 18 inches from the ground. This hard cut will result in a fully renewed plant that will still flower reliably that summer.
Why You Must Not Cut Back Old Wood Bloomers in Spring
Spring pruning of old wood hydrangeas eliminates the entire season’s bloom. The flower buds for Mopheads and Oakleaf hydrangeas are delicate structures formed months earlier and have survived the winter on the existing stems. Removing these stems means discarding the potential flowers, leaving the shrub flowerless for the year.
The correct timing for pruning these varieties is immediately after they finish flowering, typically in mid-to-late summer. Pruning at this time gives the plant the rest of the growing season to develop and set new flower buds for the following year. This post-bloom pruning should be limited to shaping the shrub and removing no more than one-third of the oldest stems at the base to encourage new growth.
If you must reduce the size of an old wood bloomer, target only the spent flower heads and prune back to the first set of large, healthy buds. Taking off too much wood will result in reduced flowering, as the largest flower buds are usually found at the tips of the previous year’s growth.
Handling Winter Damage and Deadwood
All hydrangea varieties benefit from the removal of dead, damaged, or diseased wood in the early spring. This annual cleanup is always safe to perform because dead material cannot produce flowers. Removing this deadwood improves the shrub’s appearance and overall health by increasing air circulation.
To identify dead wood, use the “scratch test” on a suspected stem. Lightly scrape the outer layer of bark: if the wood beneath is green, the stem is alive; if it is brown and brittle, the wood is dead. Cut dead stems completely back to the ground or to the point where you see the first sign of green, healthy wood. Also remove any stems that appear weak, spindly, or are crossing and rubbing against other branches.