Pruning Trees & Shrubs - Knowing When & How
Proper pruning is no more work than poor pruning and a little knowledge can go a long way to making you feel good about doing it right. There are several reasons to prune trees and shrubs including improving health and appearance, shaping young plants, renewing older shrubs, and fixing safety issues.
When to Prune
As a general rule the best time to prune deciduous trees and shrubs is in late winter or early spring when they are dormant. Pruning at this time allows you to see the shape and interior of the tree so you can see what you are doing and there is less chance of disease or insect problems. Dead branches can be removed at anytime.
There are some exceptions.
- Do not prune oak trees between April 1 and July 4th to reduce the threat of oak wilt. Go to www.forestry.umn.edu/extension for Oak Wilt updates.
- Do not prune any trees or shrubs between the time the buds swell and leaves open up.
- To minimize "bleeding" of maples, birch, ironwood, honey locust, blue beech, elm, butternut and walnut prune early in the summer after the leaves have opened.
- Do not prune spring flowering shrubs until after they have bloomed. Flower buds for the next year develop during summer months so prune right after blooming.
Evergreens (conifers) require little pruning.
- Junipers, yews, arborvitae, and hemlock - prune late spring to mid summer but avoid hot summer days.
- Spruce, fir, Douglas fir - late winter to spring.
- Pines - light green new growth (candles) in spring to early summer can be pruned back about half the length before they mature
How to Prune
An important pruning task for homeowners is to prune young trees in their formative years (1-6 years).
- Most young trees should be trained to a single central leader (with a few exceptions such as crabapples). If there are multiple leaders, reduce to one.
- Do not cut back the leader.
- Remove rubbing, crossing, crowded branches, and branches growing toward the center of the tree.
- Remove water sprouts and suckers (fast growing vertical shoots from branches or roots).
- Remove narrow-angle branches which tend to be weaker and prone to storm damage as they get larger.
Pruning small branches
- When shortening a branch or twig, cut it all the way back to a side branch or make the cut about ΒΌ inch above a bud.
- Always choose a bud facing the outside of the plant to force the new growth in that direction.
To remove large branches, use the three-cut method.
- Make the first cut on the underside of the branch about 18 inches from the trunk. Cut 1/3 of the way through the branch.
- Make the second cut about an inch farther out on the branch; cut until the branch breaks free.
- Before making the final cut removing the stub from the main stem, identify the branch collar. The branch collar grows from the stem tissue around the base of the branch. Make the final cut so that only branch tissue (wood on the branch side of the collar) is removed. Be careful to prune just beyond the branch collar, but DO NOT leave a stub.
Paul Richtman, University of Minnesota Extension Master Gardener
For more information and to see diagrams of how and where to prune go to:
Pruning Trees and Shrubs - U of MN Extension
How to Prune Trees - USDA Forest Services
How to Properly Prune Deciduous Shrubs - University of Wisconsin Extension
Seasonal Care for Trees and Shrubs in Northern US Climates - U of MN Forest Resources
