Late winter is pruning time for many trees and shrubs, but the majority of questions we receive relate to hydrangeas. When to prune depends on the type of hydrangea you have. Here are some guidelines:
Bigleaf and lacecap hydrangeas; Hydrangea macrophylla: This common hydrangea usually has pink or blue flowers, the blue shades a result of more acid soils. For a mature plant, remove the dead wood in late winter by cutting those stems to the ground. This will allow access to more air and light. Any other pruning should be completed after the flowers fade—not earlier than July; no later than the first week in August. Later pruning will destroy flower buds developing into the next blossoms.
Smooth hydrangea; Hydrangea arborescens ‘Annabelle’: Because of its untidy growth pattern most gardeners annually prune the entire plant to 6-12” from the ground. This should be done in late winter as the flowers appear on the current year’s growth.
Peegee hydrangea; Hydrangea paniculata grandiflora: Develops into a large shrub producing many smaller blooms. In early March, severe pruning, cutting back to only two buds at the base of each stem, will produce a smaller shrub with larger flowers on current year’s growth.
Oakleaf hydrangea; Hydrangea quercifolia: Native and generally left to grow its natural form. Blooms for a long period on last year’s growth. Any pruning should be done as soon as the flowers begin to fade.
For most woody plants, follow this rule: “If the plant blooms early in the season on last year’s growth, prune after it blooms—not now!” (Forsythia, for example.)
If the plant blooms later on growth that occurs this year, do only limited cutting now. Wait until after the blooms have faded before major pruning.
Article written by Glenn Palmer, Extension Master Gardener Volunteer.