Generally speaking, pruning in the spring promotes vigor and pruning in the fall retards vigour. Therefore, if you have a woody plant that needs to be more robust - such as a shrub or a small tree - you should either remove 1/3 of the growth, or coppice the plant, in early spring - as soon as the
snow is gone.
Coppicing is the practice of cutting an old or overgrown shrub ALL the way back to the ground - almost below! - to rejuvenate it. Don’t be shy! This can be done with most deciduous, multi-stem non-variegated shrubs, but avoid coppicing Lilacs and Potentillas.
Fall Pruning
If you have fruit trees and crabapples you’ll find they have less sucker growth if they’re pruned anytime after mid-August. With plum trees, pruning in late summer or early fall will also prevent the spread of the fungus known as black knot. This is especially important for the Schubert Cherry, which can be killed by the disease in just a few years.
Pruning late in the year has the added benefit of preventing damage from snow loads on upright evergreens such as Cedars and Blue Arrow Junipers. The same goes for hedges - giving them a light shear to remove the fluffy bits will help prevent snow and ice from pulling the branches apart.
How
For the health of the tree and for reducing physical strain on your body, make sure that your pruning tools are clean and sharp. Regular spraying of the blades with a 5% bleach/95% water solution will help prevent disease spread.
It is also important to think about the shape of some plants. When pruning your hedges - for example - be sure to slope the sides so they are wider at the bottom than the top. This allows sunlight to reach the whole side of the plant, promoting thicker foliage from bottom to top.
We can do terrible things to plants when we’re pruning, and if we’re using power tools we can do terrible things faster. It never hurts to get a consultation on how to prune from a professional and - if you don’t have the time to do the work yourself - it’s well worth bringing someone in who has the experience and knowledge to do the job right.
Pruning should be the ultimate expression of art and science blended together. Proper pruning will increase your property value and preserve your landscape for years to come.