Pruning Evergreens
Pruning evergreens has its own set of problems. Needle-type evergreens, such as pines and spruce, are not regenerative-type plants. If a branch dies or is cut off, it will not be replaced naturally, as there is no dormant bud to sprout and develop a new limb. This type of evergreen should not be sheared every year, as this practice results in a tree that is dense, preventing light from entering the interior of the plant. This causes massive die-back of the foliage, so that eventually the only live part of the branches is at the very ends; new growth is reduced due to decreased photosynthetic activity. Also, because of the lack of light and free air movement, these plants are at risk of some of the diseases that infect these types of plants.
While pines and spruce should not be sheared each year, there is a type of regular pruning that will remedy the tendency of Scotch and Austrian pines to develop an excessively loose appearance. Simply cutting back the candles (the expanding new growth at the ends of the branches) to one-third, one-half or three-quarters total growth as the candles are opening up and releasing the needle growth will not only slow down the overall growth of the plant but also thicken the canopy. This form of pruning is religiously carried out with bonsai gardening. This type of pruning should be done before August as pines and spruce set their buds around this time. If the candles are pruned after this date, there will be no new growth on these branches next season.
Certain evergreens such as arborvitae and chamaecyparis are susceptible to leaf burn (scorch) if sheared with hedge shears. Removing entire leaflets is more beneficial, and the plant will still retain its shape and loose appearance. This is somewhat time-consuming, but far better for the plant.
Forms of Pruning
There are many ways to break down categories of pruning, but the simplest system recognizes regular type pruning, pruning weeping forms, formative pruning, and sometimes regenerative pruning. Regular pruning encompasses removal of dead, diseased or dying wood, removal of crossing branches, cutting back of main and side branches by one-third, and removal of weak growth and unproductive material. Most plants are pruned in this fashion. Pruning weeping forms requires general thinning of the crown, complete removal of any growth from the trunk below the graft, and trimming back of branches that are trailing along the ground. The object is to achieve a haphazard look rather than an umbrella shape. Formative pruning is pruning to a desired shape or form, usually carried out on fruit trees, bonsai or topiary plants. Fruit tree pruning includes such activities as peach trees that are pruned and trained to look like a fan, or apple trees that are espaliered to create a living fence. This is often done where space is very limited. Bonsai plants are extensively shaped, as are topiary plants.
Regenerative pruning is cutting back main branches and allowing dormant buds to grow, usually required when the size or shape of a plant must be drastically adjusted. Regrowth takes a couple of years to accomplish, which can be problematic. It is often required for plants that have been clipped or sheared because such plants often outgrow their place in the landscape and make pruning difficult. While shearing is quick and easy to clean up after, it may not be the best technique to use.
A regular pruning regime will reveal all the plant’s attributes – flowers, shape, healthy foliage, interesting bark, unique growth habit, etc. This is a task that all gardeners will have to tackle at some point, but remember that plants are somewhat forgiving, so unless you are pruning a pine or spruce, the plant will grow another branch if you make a bad pruning decision. Given time, your plant will literally cover up your mistake!
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