Winter Pruning

Pruning of most deciduous nursery stock is often completed in the winter before plants break dormancy. Possible exceptions are trees species such as maples, beech, and birch, which are called “bleeding trees” because they lose considerable water and sap after pruning in the spring. Pruning shortly after leaf drop in the fall or pruning during summer months when leaves are present will control bleeding. However, reference books indicate that mostly water is lost, which causes little damage to plant health. Another reason to avoid dormant pruning on trees such as crabapple is excessive water sprouting. If they are pruned later in the year when leaves are present, less sprouting occurs.

Reasons to prune plants while they are dormant are that (1) the branch structure can be seen more easily and (2) pruning while plants are dormant stimulates growth on remaining branches. Pruning should be limited to removal of no more than a third of the total bud and leaf-bud-bearing branches. Otherwise extensive water sprouting may result. Prune out crossing, inward growing, parallel, and competing branches. Branches growing in the center of multi-laddered trees such as river birch and crapemyrtle should be removed so that attention is focused on exfoliating bark. Scaffold branches are permanent branches which make up the frame of the tree. When trees are small, tiers of branches may be 3 to 6 inches apart such as in pear cultivars. During the next two years in the field, prune to develop spacing between whorls to a foot or more, particularly for large, maturing trees. Branches should also be well spaced around the trunk. Acutely angled limbs are weaker than more horizontally growing branches and should be eliminated. Parallel branches growing in the same plane, one above the other, should also be eliminated by removing one of them. Branches growing back toward the trunk or across other branches should be removed.

Depending on the intended use, customer demand, and market, deciduous shade trees are usually limbed to 36 or 48 inches. Smaller trees used for residential landscapes usually branch lower than larger trees and may be as low as 24 inches. Boulevard and parking island trees need higher clearance than specimen and residential trees with canopies set as high as 60 or 72 inches. Lower branches should be removed each year so that the canopy is raised up gradually as the tree grows in height. Ideally, lower branches are removed before they reach 1/2 to 3/4 inches in diameter so that pruning cuts will close rapidly (Figure 4).