Pruning Shrubs

Pruning Shrubs: Deciduous

Pruning shrubs is not as difficult as many people think, but a few guidelines are helpful. The first consideration is when to prune shrubs. Late winter pruning is done on those shrubs that bloom in the summer or fall; summer or fall pruning is for those shrubs that bloom early in the year. Look at the shrub carefully and note if the new spring leaves and stems are growing well and forming new blooms along the way, or if the leaves are absent when the bud is swelling or the blossom is open.

Spring blooming shrubs form the buds for the bloom on last year’s wood. If you prune this wood off in late winter then you take the pre-blooms with it and you will have to wait another year for any flowers. Many of the spring blooming shrubs such as lilacs and forsythia both produce flowers on older wood and so should not be pruned until the blooms have finished. Do not wait too long into the summer for the pruning though as new wood, complete with next year’s blooms, will soon start forming.

Late winter or early spring is the time to prune those shrubs that produce flowers on this year’s wood. Spireas and weigelas as well as roses should all be pruned before the new growth starts.

Some shrubs rarely, if ever, need pruning to keep healthy. This group includes rhododendrons, azaleas and hydrangeas. For these shrubs only trim out dead branches or ones that are a problem such as obstructing a footpath, brushing against a window or overshadowing another plant.

To prune, it is essential to use the correct tools for the job. Small branches can be severed with a simple pair of pruning shears; larger branches may need loppers or even a saw. Always remember to wear safety glasses and other protection if you are taking off small or large branches from above your head!

Start by taking out dead branches, then problem branches;

Then look at the overall shape of the shrub. Wayward branches can be trimmed back as well as suckers that come up from the root. Always trim branches back to where they join another branch, or back to a main stem.

Sometimes a shrub becomes too crowded in the center and this can cause problems, so selectively prune out a few branches in the middle of the canopy back to a main stem. Remove any horizontal branches that have grown, or are likely to grow, into the center of the shrub. If the shrub is way overgrown then you will want to consider taking serious pruning action. Look at the base of the shrub and note how many large stems emanate from the base. Divide this number by three. Take out this number of branches at the base of the shrub. Next year take the same number of the oldest branches out and finally take the last one third out in year three. This will encourage new growth which will be vibrant and able to produce more flowers than old growth, while at the same time it keeps a decent size shrub in your landscape.

Next time, we will deal with pruning evergreen shrubs.

©Text and photograph by Kate Copsey, May, 2006. Reproduction without permission prohibited.