AUBURN, Ala.—The month of February brings blooms of many different shapes and sizes, a sure sign spring is around the corner. While daffodils and camellias are blooming in bright colors, gardeners may find themselves spending more time readying the flowerbeds.
While it may be tempting, February is not the time to prune your hydrangea bushes. Understanding flower development for each hydrangea species is helpful. Some hydrangeas bloom on “old wood” while others bloom on “new wood.”
Hydrangea Species and Flower Buds
Blooms on “old wood” are produced by buds set last summer. Flower buds forming on this year’s growth appear on “new wood.“
Alabama Cooperative Extension System Home Grounds team leader Kerry Smith, said it is best to prune shrubs that bloom on old wood shortly after current flowering to avoid removing next year’s developing buds.
“The next year’s flower buds begin forming in August,” Smith said. “If a shrub blooms on new wood, prune in late winter or in spring to stimulate new growth for additional blooms.”
Annual, general maintenance on bigleaf and oakleaf hydrangeas is recommended. Remove all dead wood and cut about one-quarter to one-third of the older stems to the ground. This improves plant vigor, overall shape and bloom volume.
Smith said using July 4 as the last date for pruning these two species is an easy way to remember it.
Bigleaf and oakleaf bloom on old wood. A few bigleaf hydrangeas bloom on both old and new wood, like ‘Endless Summer’ and others. Choose these if you live in an area prone to late frosts.
Both smooth and panicle hydrangeas bloom on new wood. Cut smooth hydrangea 6 to 12 inches from the ground, or at half its height, every year in late winter or early spring. The height for pruning these is strictly personal preference. Prune after initial flowering to stimulate a second flower flush.
Panicle hydrangea, sometimes called PeeGee, is most effective in tree form. Remove lower suckers and up to one-half of older stems for greater flowering.
Hydrangea Hardiness and Cold Damage
The bigleaf hydrangea is the most cold-sensitive species. It suffers with early or late freezes because the flower buds have a weak dormancy.
Surprise warm weather in winter or early spring causes the buds to emerge from dormancy, grow and become more susceptible to freeze damage. This damage results in fewer or no flowers because this year’s flower bug grew on buds formed last summer.
Smith said the remedy is careful site and cultivar selection.
“If this type of weather is common in your landscape, plant bigleaf hydrangea on northern and eastern slopes under tall pines to reduce the temperature fluctuations that cause early bud break,” she said.
Homeowners can also choose resilient cultivars that either bloom later or produce new buds for the current season.
Feature photo by Swetlana Wall/Shutterstock.com. Winter Hydrangea Image by Phil Darby/Shutterstock.com.