A frequent question we receive is about pruning shrubs. Proper pruning maintains an attractive shape and keeps the shrub healthy. Pruning thins out branches allowing new growth to receive sunlight and it promotes good air circulation which prevents diseases. Knowing why we prune shrubs is important but knowing when to perform this task and how to do it properly is equally as vital.
As to when to prune shrubs I always view this as a spring to early summer job. Pruning in the fall can be harmful as the purpose of pruning is to promote growth and the last thing you want to do is to promote new growth which is likely to be damaged or killed by colder weather. This damage can weaken the shrub and eventually lead to its demise. It is also particularly important not to prune spring-flowering shrubs, such as Azaleas and Lilacs, in the fall as you are literally cutting the flowers off.
Now that we understand why we prune shrubs and when we should do it the final question to answer is how do we perform this task? First, before you start cutting take a step back and look at the shape of the shrub. As you scan the shrub take note of broken or damaged branches which should be removed. When you start pruning you’ll want to make cuts at a 45-degree angle about ¼ of an inch above a flower bud on the branch you are pruning. You can use a hand pruner for most cuts but if you have branches that are more than a ½ inch thick a lopping tool might be needed to make clean cuts.
Finally, let’s talk about how to apply these pruning tips to some well-known plants:
Crape Myrtles - Crape Myrtles should be pruned late in the winter or early in the spring. You can wait until the first growth emerges but you don’t want to wait too long after this occurs or you will negatively impact the shrub’s flowers. All Crape Myrtles should be pruned as this has been found to produce more flowers but prune no more than 1/3 of the shrub at any one time.
Hydrangeas - Hydrangeas are a little more complicated in terms of when to prune them. Old wood hydrangea varieties should be pruned immediately after they finish blooming in the summer. Old wood hydrangeas develop their flower buds for next year in August and September and pruning them too late in the season will lead to fewer blooms next year. The other variety of hydrangea is known as a new wood hydrangea. These hydrangeas form their flower buds on new growth so it is easier to prune these shrubs and they are much more likely to bloom regardless of when they are pruned. I would recommend pruning late in the winter and apply the same 1/3 pruning rule that we’ve discussed previously.
Azaleas - One of my all-time favorites it disappoints me when I see them closely sheared and shaped as that impacts their beautiful flowers. I suggest keeping them tidy but not too closely pruned and any shaping should be done immediately after they finish flowering to ensure that you are not cutting off next year’s flower buds.
Please also check out our related article on how to prune lilacs and if you have additional questions about pruning shrubs please reach out to us through the “ask us” page of our website or on Facebook.