Pruning is the selective removal of plant parts to improve the health, shape, and flowering capability of a shrub. For flowering bushes, the timing of this action is the single most important factor determining the abundance of the next bloom cycle. Making a cut at the wrong time can inadvertently remove the very buds that would have produced flowers. The correct schedule depends entirely on whether the shrub flowers on “old wood” or “new wood.”
Timing Pruning for Early-Spring Bloomers (Old Wood)
Shrubs that bloom early in the spring, often before their leaves have fully developed, flower on “old wood.” This means the plant forms its flower buds on the stems that grew during the previous summer and fall growing season. These buds are set and mature throughout the fall and winter, ready to open as soon as temperatures rise in spring.
The correct time to prune these bushes is immediately after the flowers have faded, typically in late spring or early summer. Pruning during this brief window allows the shrub time to recover, produce new stems, and successfully set the next year’s flower buds before dormancy arrives. Cutting these shrubs in the late fall, winter, or early spring will remove the pre-formed flower buds, resulting in a drastically reduced bloom the following season.
Timing Pruning for Summer and Fall Bloomers (New Wood)
Bushes that flower later in the season, generally from mid-summer through fall, bloom on “new wood.” This means the shrub develops its flower buds on the growth that emerges during the current spring and summer growing season. The plant prioritizes new vegetative growth first, and then the flower buds form on the tips or along the sides of these fresh stems later in the year.
The ideal time for pruning these new wood bloomers is during the plant’s dormant period, typically in late winter or very early spring before any new growth begins. This timing encourages the plant to produce vigorous new shoots as soon as the weather warms, maximizing the number of flowering shoots. Pruning can be done aggressively on many of these varieties to rejuvenate the shrub or control its size, as the subsequent growth will carry the season’s flowers.
Essential Year-Round Pruning (Health and Safety)
Some pruning must occur without regard for the flowering schedule, specifically any cuts made to maintain the plant’s health and structural integrity. The immediate removal of any dead, diseased, or damaged wood is necessary at any time of the year. Delaying these cuts risks the spread of pathogens or provides entry points for pests into the plant’s healthy tissue.
A broken branch from a storm or a stem showing signs of fungal infection should be cut back immediately to healthy wood. Similarly, any branches that are crossing and rubbing against each other should be removed, as this friction creates open wounds that can invite disease. These types of cuts are for preventing further deterioration and ensuring the long-term survival of the bush.
Quick Guide: Common Flowering Bush Examples
Determining the correct time to prune depends on classifying common bushes as either old wood or new wood bloomers. Forsythia and Lilac, which display their flowers early in the spring, are classic examples of old wood bloomers and should be pruned right after their blooms finish. Bigleaf Hydrangea (Hydrangea macrophylla) also typically flowers on old wood, making its correct pruning time immediately post-bloom, though some re-blooming cultivars are exceptions.
Conversely, Panicle Hydrangea (Hydrangea paniculata) and Rose of Sharon (Hibiscus syriacus) are new wood bloomers. Shrub roses, particularly the modern varieties that bloom repeatedly, also generally flower on new wood, making late winter the optimal time for their main structural pruning.