As we’re looking forward to Spring, and hoping it’s around the corner soon, late winter is a good time to do some pruning, particularly on deciduous trees and shrubs. In Winter we can view the overall structure of a tree or shrub, without it being obscured by leaves. It’s also healthier for the tree to be pruned while dormant, before the sap begins to flow in Spring. Pruning in the summer will take away some of the plant’s energy (in leaves), this is stored safely in the roots in the winter.
Prune trees and shrubs that bloom on new wood
First of all, make sure that you’re not pruning a tree or shrub that will be blooming soon, like Forsythia, or Western Redbud (Cercis Occidentalis) or the Star Magnolia (Magnolia stellata), unless there are some dead or diseased branches that need to come out. Plan on pruning them after they bloom. Similarly, don’t prune your Rhododendrons now, or you’ll cut off all those beautiful blooms.
Secondly, be clear on why you’re pruning. Maybe the tree’s size needs to be controlled, or the branches need thinning, so that lower branches, or plants growing beneath can get more light. Or perhaps there are some structural defects that need to be addressed; dead or diseased branches to remove, or crossing branches growing in the wrong direction. Regular pruning will help light penetrate the canopy, and air circulate, resulting in a healthier tree. Over time you will develop an eye for the pruning cuts that should be made. But be careful of over pruning, you should prune out no more than a quarter of the canopy or even less, it’s best to be conservative on this. If you are not sure, consult an Arborist, there is great value in a well pruned tree!
Selecting the correct species to prune in Winter
Trees and shrubs you can prune right now tend to bloom in summer; June and beyond. Crape Myrtles (Lagerstroemia indica), which are late summer bloomers and trees, such as the Katsura tree(Cercidiphyllum japonicum), Smoke tree (Cotinus species), Hornbeams (Carpinus species) and Oaks (Quercus species). Shrubs such as Buddleia, Abelia, Caryopteris, and Hibiscus can be pruned now. Fruit trees, such as Apples and Pears can also be pruned. Since they are grown for fruit, the reason for pruning is to access fruit, and to develop a strong leader and well-spaced scaffold branches to bear fruit.
These plants will bloom on this year’s growth, so there’s no danger of pruning off blooms. Often there are spent blooms to trim back, and pruning will also help to control the size of shrubs and trees, encouraging new growth, and keeping them more compact, and less woody.
Some evergreen trees and shrubs, such as Spruce (Picea), Fir (Abies), Yew (Taxus), Holly (Ilex), and Boxwoods (Buxus) can also be pruned in late winter, while dormant.
As you’re pruning, always keep in mind the habit (the way the plant wants to grow naturally), and try to accentuate its features, and allow it space to grow.
The International Society of Arboriculture (ISA), has a handy guide on tree pruning for the consumer: