I’m in Toronto, and I would like to prune three pine trees in front of my house(see pictures attached). When is the best time of year to prune these trees and where on the branch should they be cut? In the past I always pruned mid-summer after the new growth has matured. The two blued pines on the left I would like to keep them in the shape of an umbrella. The dark green one on the right I would like to keep that in the shape of a round ball.
Thank you for your question. Since we have many questions every year on this topic, I have simply copied one of our previous answers. For more information, try going to our home page: torontomastergardeners.ca and entering your query word in the Search box under Find It Here. I hope you will enjoy reading all about evergreen pruning.
“Most pines are best pruned in mid-June before the needles start to unfold. During this time, the new growth looks like candles. When these shoots are soft, cut them back to one-half to one-third of their length. This helps to control the length of subsequent growth for the season. New terminal buds will form at the cut ends by the end of the growing season and spread out from these points the following year.
Spruce can be pruned by cutting the shoot back to a lateral bud in early spring before growth starts. Generally in mid-May to early June, before new buds for next year’s growth have been formed. Growth will continue on from that bud as spring progresses. Pruning half of the new growth early in the spring when the new growth has extended will increase the density of the tree similar as with the pines.
Whenever possible, avoid pruning evergreen trees in late summer and early fall. Pruning at this time can stimulate new growth that may not harden off before winter, and thus may be damaged or killed by the cold.”
A great reference for pruning evergreens can be found at the Agriculture and Agri-Food Canada’s Website: Pruning trees and shrubs