As the season approaches its end, a common question that comes up is how to care for plants in the landscape during the off-season. Specifically, when do you prune your plants? Unfortunately, the answer is not the same for each plant. Depending on the kind of plant and variety, you want to prune at different times of the year. Pruning in the wrong season can lead to stunted growth and lack of flowers. To make things easier for you, we decided to put together a list of common landscaping plants, shrubs, and trees and when to prune them! Hopefully this will help guide you as you clean out your gardens!
With perennials, you can take off flowers as they fade (also called deadheading) during the spring and summer. This can help the perennial push out another cycle of blooms in the growing season. After the season is done, you can cut the perennials back close to the to make them look clean in your landscape. (Some flowering perennials do have specific needs though, so if you are unsure about a flower you can always give us a call!)
Depending on what type of hydrangea you have, the pruning time is different. If you have the pink/blue/white mophead or lacecaps, they bloom on old wood. This means that if you prune them in winter or early spring, you’ll be taking off the flower buds. So these types should be pruned before midsummer.
Reblooming types like the “Endless Summer Series, bloom on new and old growth, so the pruning time is less important. Those you can prune whenever you want to clean them up a bit.
Paniculata and arborescen types (so like “Limelights” and “Strawberry Sundae”, or “Annabelles”) flower on new wood, so they can be pruned any time other than just before they bloom. So we would suggest you prune these in winter/ very early spring.
Spring-flowing Trees and Shrubs:
Common spring flowers trees and shrubs like lilacs and rhododendrons bear flowers on wood from the previous year. So the best time to prune them is right after they finish blooming in spring. With these types, if you prune in winter or any other time, you will be taking the flower blooms off for the next year.
Summer Blooming Trees and Shrubs:
Examples of these shrubs and trees would be a butterfly bush or potentilla. They produce their flowers on new growth from the current season, so you can prune them when they are dormant (winter) or early spring just before they start pushing out new growth again.
Shrubs without blooms:
Common examples of shrubs without blooms would be a barberry or burning bush. You can prune these back almost any time except late fall (late fall pruning will cause new growth late in the season to not be hardened off for winter, causing that new growth to die). The best time to prune these would be when they are dormant during winter.
If you have an old type of rose or climbing rose that blooms once per year, you want to prune these right after they finish blooming (otherwise you risk cutting off the buds for next year). However, if you have shrub roses, tea roses, or any of the more recent varieties that bloom multiple times in a year, you can continually prune them during the season to shape the bush. If you want to do more aggressive cutting back, prune them in early spring.
If you have a hedge plant such as a boxwood, you want to prune and shear these during the early part of the growing season. You can shear slightly during the summer as well, but you want to stop pruning around the beginning of September (any new growth after that will not be hardened off for winter).
This category would include plants like arborvitaes, junipers, yew, fir, spruce, and false cypress. It is best to prune these evergreens early in the growing season.
With perennials ornamental grasses, we usually suggest leaving them during winter, as they provide interest to your landscape in the winter months. They do not need to be cut back (the old grass actually provides insulation to the plant during the cold winters), however if you are a gardener who likes everything looking clean, you can cut back your grasses very early spring (4-6 inches from the ground) before the new grow starts to push out.