Pruning Ornamental Trees
Unlike pruning hedges or many fruit trees, pruning ornamental trees—such as Dogwood, Flowering Cherry, Magnolia, Snowbell, or Japanese Maple—involves mostly thinning to enhance natural branching patterns, open up views to trunks, and reduce the overall density. Although the growth habits vary between types of trees, the basic principles of thinning and redirecting apply to most. Some trees need very little, if any, pruning. For the rest that do need pruning, here are the basics to get you started.
WHY PRUNE YOUR TREES?
Redirect growth energy to a desired direction. Reveal beauty of branching patterns by selective thinning. Allow greater light penetration and air circulation. Reduce risk of wind and snow breakage.
WHEN TO PRUNE?
Winter: any time between total leaf fall and the breaking open of the first spring buds. Good for major clean-out and thinning. Fewer bugs to swat or bulbs to trample. Watch for excessive running sap.
Summer: after leaves are full size, through early September. Good to see foliage masses for thinning and layering. Easier to identify dead branches. Generally stimulates growth less than winter pruning.
Flowering trees: ideally soon after flowering, but light thinning will not impact future flowering. Anytime of year: remove dead or problem branches.
HOW MUCH TO REMOVE?
Do less than you think you need to. Try not to remove more than 1/4 of the volume of the living crown in any one year (some professionals recommend even less). More may cause oversprouting. Anything dead should be removed, of course.
3 BASIC STEPS
1. Clean Out: Remove branches which are dead, diseased, broken, crossing (rubbing on each other) or out of character with the rest of the tree.
2. Selectively Thin: Open up light and air circulation. Make the interior more transparent but not stripped clean. Balance the branch density around the tree.
3. Shape and Layer: On more horizontal branching trees: enhance “cloud formations” and spaces between them. On more vertical growers: lightly thin between major branches. Open up views of attractive/unique trunks and branches, such as at major crotches.
MISCELLANEOUS WISDOM
Don’t fight your tree’s will to grow to a certain size. Work with it, or replace tree with something smaller.
Safety! Eye protection from branches.
Keep your tools sharpened for clean cuts, less stress on your hands.
Work from inside out, bottom to top. Start by removing small inside branches. Work up to larger if necessary. You can shake or trace the branch before cutting to anticipate the effect of its removal.
Leave minimal length of dead end stubs.
Work around the plant at least twice (if possible). You will notice different details each time.
Observe how the tree grows in density,
then start thinning from the inside out:
Work from bottom to top, smaller branches to larger. This typically gives a more natural-looking result and helps you decide which larger branches to cut, if necessary. Avoid over-thinning. Make it more “transparent” or “breathable” but not sparse.
Redirecting branch growth:
A “thinning” cut removes an entire branch, rather than a '‘heading“ cut which shortens the branch (inducing more density). This redirects growth energy into a branch direction you choose.
Half-Diameter Principle:
Redirect to a side branch at least one half the diameter of the branch you’re cutting.
AVOID: Cut A is above too small of a side branch: might stimulate oversprouting, or branch segment to die.
BETTER: Cut B is above a larger side branch (at least half diameter): sends growth energy into that branch.
3-step cut for large branches
To avoid tearing bark as the heavy branch falls. To allow proper healing, don’t cut into or damage the branch collar.
