Winter is a great time to prune deciduous trees. Once the leaves have fallen, it is easy to see the structure of the tree and determine what branches should be removed.
There are easy targets for what to prune first. Broken, damaged or diseased limbs should be removed. Branches that cross each other can rub and cause lesions, increasing susceptibility to disease, Criss-crossing branches are also aesthetically undesirable, creating a chaotic appearance. Prune them during the winter while they are easy to see.
For young trees, winter is the optimum time to do structural pruning. Storm- damaged trees might need corrective pruning to restore a pleasing shape. Consider hiring a certified arborist to determine the best path to restore the structure of a large, damaged tree. For an extensive discussion of structural pruning, read Colorado State University Garden Note 616 Pruning Mature Shade Trees.
Conifer trees and shrubs generally need little structural pruning. Small conifers such as Mugo pines benefit from “pinching” techniques to encourage more compact growth. Using your fingers, snap off one-third of the new growth when that growth is still in the candle stage. Do not use pruners or a knife since cuts may give a brown tip appearance. For more information read Colorado State University Garden Note 618 Pruning Evergreens.
Deciduous shrubs can benefit from dormant season pruning. Shrubs can be pruned to improve the aesthetic structure of the shrubs; flowering shrubs can be pruned to increase the amount of flower production.
Flowering shrubs can be divided into two categories: shrubs that bloom on old wood and those that bloom on new wood.
Early blooming shrubs (prior to June 15) have buds that formed in the prior year; they are generally pruned after they bloom. Pruning them in winter will remove spring blooms, but there may be times when it makes sense to prune these during winter; an example would be an old woody lilac that is no longer blooming because it is too woody.
An aggressive pruning will remove blooms this year, but it will likely produce a flush of new rejuvenated foliage that will bloom in future years. Only remove a third of the older stems at a time.
Later blooming shrubs bloom on new growth and late winter pruning will encourage the new growth and the blossoms. For an extensive discussion of structural pruning read Colorado State University Garden Note 619 Pruning Flowering Shrubs.
Broadleaf evergreen shrubs such as Boxwood and Oregon Grape Holly should be pruned no earlier than two weeks before our last spring freeze. Earlier pruning can encourage tender new growth that can be damaged by late spring frosts. Prune in early May.
Submit gardening questions to firstname.lastname@example.org. They will be answered via our remote help desk system. The in-person Help Desk is closed for the winter; it will reopen in spring. Find us on Facebook at Colorado Master Gardeners – El Paso County.
Submit gardening questions to email@example.com . They will be answered via our remote help desk system. The in-person Help Desk is closed for the winter; it will reopen in spring. Find us on Facebook at Colorado Master Gardeners – El Paso County.