Pruning These Shrubs In Winter Will Ruin Spring Blooms

From perennials that need to be pruned in the fall to trees that need a light trim in the dead of winter, a gardener's pruning shears never get any rest. However, it can be a little dizzying trying to figure out exactly when to prune everything in your garden. Of all the mistakes to avoid when pruning your plants, one of the biggest is pruning at the wrong time, especially when it comes to pruning spring-flowering plants like azaleas (Rhododendron spp.) and lilacs (Syringa vulgaris). Since these shrubs set flower buds for next year in the summer and fall, pruning them in the winter can ruin their blooms.

Spring-flowering shrubs and trees, whether they are evergreens like rhododendrons (Rhododendron spp.) or deciduous shrubs like fothergilla (Fothergilla gardenii), are best pruned immediately after they flower. They flower on old growth, so pruning immediately after flowering gives them a chance to form new buds during the summer and fall to support more flowers the following spring. Pruning too late can also lead to problems with a plant's dormancy, leaving it vulnerable to disease and cold weather.

As gardeners, we prune for a lot of different reasons, and to the untrained eye, it might seem like we are hacking and whacking away at the plants in our garden without rhyme or reason. In reality, there are solid motivations for pruning trees and shrubs, whether it's to control growth, shape the plant, or remove dead branches.

A good rule to remember before you prune is to start with the three D's, which stand for dead, damaged, or diseased. You can and should remove branches with these traits at any time of year to prevent problems like insect infestations, but after that, you need to take the plant's life cycle into account before you start clipping away.

In addition to the previously mentioned azaleas, rhododendrons, lilacs, and fothergilla, we'll add some other early spring-flowering plants to the list of shrubs that shouldn't be pruned in the winter; however, this list is by no means exhaustive. Some of the more common plants you'll find in the garden that flower early in the spring and can be ruined by a winter pruning include forsythias (Forsythia spp.), mockoranges (Philadelphus coronarius), kerrias (Kerria japonica), magnolias (Magnolia spp.), and weigelas (Weigela florida).

Instead, prune these flowering shrubs in the few weeks following the bloom period, using the same methods as those you would normally use to shape the shrub or encourage new growth. Cut out old stems that aren't producing as many blooms, being sure to follow the one-third pruning rule of removing no more than a third of each branch.