Deciduous trees and shrubs are simply those that shed their leaves at the end of each growing season, as opposed to evergreens that keep their foliage year around. As with all plants, you should have a plan before doing any pruning. Good reasons to prune would be to remove damaged or dead branches, to shape young trees and shrubs or to thin excessive growth. For pruning purposes, deciduous plants are divided into blooming and non-blooming.
Generally, the best time to prune anything deciduous is in late winter or early spring just before new growth when the leaves emerge. The worst possible time to prune is right after everything leafs out, since the plants have just used up most of their stored energy and haven’t had time to replace it. Fall used to be thought of as a good time to prune deciduous material, but spring really is better if possible. Plants store lots of energy in twiggy growth to help them over winter, and cuts will heal more quickly when the plant is getting ready to grow as opposed to shutting down.
If a deciduous plant blooms very early in the spring, such as lilacs and old-fashioned Bridal wreath spirea, it is blooming on last year’s growth and should be pruned right after it blooms. There are a few plants, such as weigela, that bloom on old wood but bloom later in the season. They can be pruned lightly in spring or after they have bloomed. Another large group of blooming deciduous plants form their flowers on the current season’s new growth, such as potentilla and the low, mound-type spireas. These plants are best pruned in early spring before they leaf out. If you prune them at the wrong time the only adverse effect will be that you may lose the blooms. You may want to consider letting the pruning wait until next season, but sometimes we just don’t have a choice and have to prune when we can.
Formal hedges can usually be pruned lightly in late spring and again in midsummer to keep them uniform in appearance. Often, lilacs and other blooming shrubs are used for informal hedging, and they should be pruned at their appropriate time to preserve their blooms.
Should I prune a newly planted tree or shrub? When you are buying from a reputable nursery, your new plant material will already be properly pruned. Other than removing any damaged branches, do not prune a plant until it has been in the ground a full growing season. Pruning bare root plants isn’t necessary either. Recent research has changed how we prune bare root plants. It used to be common practice to prune the tops of new bare rootstock, thinking this would give them less to support as they reestablished their root systems. We now understand that bare root plants need all their buds to provide leaves for gathering energy to grow. These plants were probably properly trimmed as they were grown, so they shouldn’t need much, if anything. When you are planting bare root plants, simply remove any damaged branches and roots and wait until the next growing season to do anything further.
Sealing wounds with pruning paint is another common practice that has fallen out of favor. We now know that in most cases, clean, unsealed wounds will heal more quickly and with less disease and decay than will those covered with pruning paint. Unless you are dealing with trees and shrubs that are known to be susceptible to disease transmission through wounds, do not seal the wound.
There are varieties of trees and shrubs that should be sealed. Special care needs to be taken to try to minimize transmission of Dutch elm disease, oak wilt and fireblight. These diseases can be deadly and often enter plants through fresh wounds. They are spread from one tree to another most often by insects. To be safe, avoid all pruning during the growing season and seal all injuries to susceptible trees during the growing season. American elms are susceptible to Dutch elm disease. All oaks are susceptible to oak wilt disease, but especially red oaks. Fireblight most commonly affects mountain ash, hawthorns, crabapples, apples and several other varieties of fruit trees. The University currently recommends pruning oaks and elms only while the plants are fully dormant; from late fall through early March. January and February are good target months for pruning fireblight susceptible plants.
If you need to prune out large branches or prune well beyond your reach, consider calling a professional.
Additional Bachman’s Information
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Pole Pruners and Loppers
Quality Gardening Tools and Gloves
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