By Kristopher Wulff, Master Gardener
Late winter or early spring before growth begins is the best time to prune woody landscape plants or trees. With deciduous plants it is easier to see the framework of the plant while the leaves are off. Pruning wounds tend to heal quickly in the early spring. Insect and disease activity is low so there is less chance of disease or insect infestation.
Pruning at the wrong time of the year will not kill the plant but repeated improper pruning can damage or cause stress to plants and trees. Stressed plants and trees are more susceptible to fungal, bacterial or insect damage. So, pruning should be done when the results are optimal for plant growth. Optimal times will vary according to weather conditions. Heavy and prolonged cold snaps will damage newly pruned trees, shrubs and plants. This is called ‘winter kill’. ‘Winter kill’ can be avoided by pruning later in winter thus avoiding the cold snaps common in the Midwest.
Plants and ornamental trees which benefit from late winter/early spring pruning:
- Deciduous trees which shed their leaves in the fall, like maple, birch and walnut, can be pruned from November through the first week in April.
- Flowering shrubs should be pruned according to their flowering time and to allow for better light and air circulation. Spring blooming shrubs should be pruned right after flowering or no later than early summer. Summer blooming shrubs should be pruned right after blooming and no later than early Fall. This will allow the shrub to harden off and produce new buds for the next flowering season.
- Pruning narrow leaved evergreens, such as hemlock, spruce and pine can prove to be difficult and also unnecessary.
- Broadleaved evergreens, such as Rhododendron, Holly, Japanese Pieris or Boxwood require little if any pruning except to removed dead or damaged branches. You may also prune to achieve the desired visual effect. Deadheading helps produce more flowers for the next year. Simply snap off the old flower with your fingers being careful not to damage the developing leaves at the base of the spent blossom.
- Pruning vines is usually needed to limit growth, thin branches and remove dead or damaged wood. Pruning most vines, including summer blooming clematis, should take place in late winter or early spring. Prune all old stems by 1/3 to rejuvenate.
- Groundcovers rarely require pruning. Pruning is necessary only when there are dead or diseased plants or there is a need to keep these plants from becoming too invasive.
- Most perennials should be deadheaded throughout the entire season and shaped for desired effect. Once a perennial is dormant it may be cut back to 3 – 4 inches height.