pruning
General Pruning
Pruning is done to remove diseased or dead wood, to eliminate crossing branches, to make some evergreens bushier and to shape unruly trees. If done well, it enhances the appearance and health of the tree; if done badly, it can introduce infections and shorten the tree's life. It isn't, however, difficult to learn how to prune well. Pruning is actually quite satisfying and interesting. Creating a shape for a tree that is pleasing and natural can be a work of art.
Every branch needs a place to be. If a branch is close to or already touching or crossing another, it will get worse as it grows. Removing or shortening one or both will create needed space. It also allows air circulation and sunlight, both necessary for leaf growth, to enter the inside of the tree. Dead branches are a potential place for disease to grow, and are best removed. Already diseased branches must be removed if the problem is not to spread to the rest of the tree and possibly neighboring ones, as diseases can spread by insects and wind.
There are a few easy rules for pruning. A branch to be removed completely, or back to a much larger branch, it is cut at the outside of the collar, a wrinkled area where it joins the trunk. A branch that is to be shortened is cut just beyond a smaller branch, which will be at the end, and at the angle of that branch. A few years after purchasing a young tree, it is a good idea to evaluate the tree's structure and create a 'backbone' for future growth. Look at the tree from several directions, before it leafs out in the spring, and prune to allow each branch future branch space, and shorten to a practical size and natural shape of that tree. A tree should never look 'pruned' after you are finished, simply tidier and nicely shaped. If this is repeated periodically, the tree will rarely need drastic pruning.
Most deciduous trees and shrubs are pruned in the spring, before they leaf out. Exceptions are birch and maple, which are pruned in July, after rapid spring growth finishes. They will drip copious amounts of sap if pruned in the spring. Shrubs that flower in the spring on buds that are formed in the fall, such as Nanking cherry, lilac, some roses, and white flowering spireas, are pruned after they bloom. Shrubs that flower in the summer, such as pink flowering spireas, most shrub roses, and potentilla, are pruned when green buds appear. Any winter tip kill is removed and branches trimmed to an appropriate size and shape. Pine trees and shrubs have new growth called candles that are snapped in half in June to make a somewhat bushier appearance and compact shape. Spruce trees are rarely pruned, although many people remove a few of the lower branches when most of the needles have died. Junipers and cedars may be sheared a little, but remember not to remove too many new needles.
Pruning shears are used for small cuts and should be sharpened frequently enough to make clean cuts. Somewhat larger branches may be removed with lopping shears, or a saw. If a large branch is to be removed completely, make an upwards cut a foot or so beyond the trunk, half way through the branch. Then cut downwards further from that cut. The branch will break off when it is being cut downwards, and default to the upwards cut, but not damage the trunk. The final cut can be made without ripping bark off the tree as it falls.
Keep pruning tools clean and sharp. If the tree is diseased, clean after every cut by dipping into a solution of one part bleach to ten parts water. If you are not sure how to prune your tree, call a certified arborist.
Hedges
Newly planted hedges such as Cotoneaster, Caragana, Lilac, and Cranberry; should be pruned back to encourage lateral branching which creates a fuller hedge more rapidly. As your hedge develops trim it so that the base is wider than the top. This allows sufficient sunlight to reach all leaf surfaces, preventing the base of the hedge from becoming open and sparse. Hedge shearing can be carried out at any time during the growing season. Older hedges in need of rejuvenation are more easily thinned out during the dormant season, in the early spring before new growth appears or in the fall after the leaves have fallen.
Shrubs that Flower on Old Wood
Shrubs that flower on old wood in the spring such as Forsythia, Double Flowering Plum, Nanking Cherry, or Lilac, for example, should be pruned as soon as flowering is finished. Pruning at any other time of the year will remove the dormant flower buds. Flower buds for most shrubs are formed on previous year's growth. White Spireas such as Bridal Wreath, Garland, and Three-Lobed also flower on old wood. Any other shrub that flowers in the summer on old wood should be pruned immediately after flowering. To prune older shrubs, usually requiring thinning, occasionally remove entire large branches by cutting them out at the base.
Shrubs that Flower on New Wood
Shrubs that bloom on new wood, such as Elders, Hydrangea, Dwarf Pink Spireas (S. bumalda and japonica cultivars), Group C Clematis jackmannii, and most roses including Hybrid Teas and Parkland Series; may be sheared to close to ground level in the spring to remove old wood. Flower buds are formed on current year's growth. All other shrubs not listed above bloom on old wood. Suckers which emerge from below ground are removed during the summer, as they originate from the root stock, not the plant grafted on to it.
Shade Trees
Shade trees should be trained when they are still young. By shaping shade trees early, unwanted lower branches, crossing or rubbing branches, and branches growing in the wrong location or direction are eliminated. Most shade or ornamental trees prefer to be pruned during the dormant season, in early spring. Birch and Maple (which are called "bleeders"), are exceptions, however. These species should be pruned in mid-summer, usually in July or August. Pruning cuts on Birch and Maple do not heal quickly because they bleed sap if pruned before their leaves are fully expanded. Most shade trees, if properly located and pruned when young, may require less pruning when mature. If you do have large trees requiring pruning, we recommend you consult a professional pruning service.
Fruit Trees
Fruit trees such as Apple, Plum, or Pear, are pruned during the dormant season in early spring to encourage vigorous growth and to create a better producing tree. Prune fruit trees so that all parts of the tree receive adequate sunlight. Unwanted lower branches, crossing or rubbing branches, and branches growing in the wrong direction or location should be removed when the tree is young. Any suckers growing from the roots or water sprouts growing from the trunk should also be removed. To prevent fruit from overloading and breaking permanent branches the smaller, outside branches should be also be thinned. Evergreens
The new growth on pines, called "candles", should be cut in half in June, after the new growth has hardened, to encourage a compact shape. Cedars and junipers may be shaped at any time. The long soft, new growth on spruce may be shortened to shape it, or minimize growth, in June. If the leader of a spruce is damaged or removed, a new one may be formed by tying a sturdy stick to the trunk, extending it above the top of the tree, and bending and tying one top branch up to the stick. You can avoid having to keep evergreens smaller than their natural size by choosing varieties that have an appropriate mature size.
Tip
Trees are so often planted in the wrong places, with little or no thought to mature size, that the answer seems to be to prune it to keep it small. This is a short term, frustrating solution that ultimately doesn't work. Trees are genetically programmed to reach a certain adult size. Removing a large proportion of the branches means that the tree has fewer places to put needles or leaves that are necessary for photosynthesis. The roots absorb water and nutrients from the soil, but there aren't enough leaves or needles to absorb sunlight, which the plant needs for survival. Often, it is better to replace a tree that is outgrowing its space and replace it with a more appropriate tree.
Spruce trees are a perfect example of this. Those cute little trees that look so perfect in a flower bed will grow to twelve feet wide and thirty-five feet high! The needles on the inside of the tree die every fall. This is a natural occurrence and not an indication of poor health. Each spring, new needles grow on the tips of the branches. If these are removed, as the oldest needles die, the tree will resemble a telephone pole with green needles only on the ends. If a branch doesn't have enough needles, it will begin to die.