Pruning shrubs and trees
March is considered the late dormant season of winter and the best time to do pruning on our shrubs and trees (especially deciduous trees -- those which lose their leaves). It is best to have pruning done by April 1, to avoid oak wilt disease, stem cankers, and fireblight. Pruning in late winter, just before the spring growth, leaves the fresh cuts exposed for a short time, as the new growth begins the wound-sealing process. Being able to see the structure of trees and shrubs without their leaves also makes pruning decisions easier.
When pruning a branch or twig, cut it back to a side branch or make the cut about 1/4 inch above a bud. Always prune above a bud that faces the outside of the plant to force the new branch to grow in an outward direction, rather then into the center of the tree or shrub. Cuts that are not made at a side branch or 1/4 above a bud will leave a stub branch which will dry out and die, or provide an opportunity for disease to enter the branch.
Young trees and shrubs may need pruning especially if they have been damaged by deer, snow or other natural causes. Prune to remove dead or diseased branches, branch stubs, branches which are rubbing, water sprouts growing off branches, suckers which are growing up from the base, closely spaced branches, and branches which have weak or narrow crotches. If a tree has suffered damage, the earlier in its life it is pruned, the quicker it can begin to recover and grow into a well shaped tree. Some trees will take a few years of careful pruning to recover.
Rubbing branches need to be pruned because the rubbing causes continual wounds to the bark of the tree itself and creates an area where pests and disease can enter. Dead and diseased branches need to be cut back to about six inches into live healthy wood. If you do not know where the healthy wood is, scrape the bark with your pruner. If it is brown, the wood is still dead, if it is green, it is alive. When pruning in diseased wood, pruning tools need to be dipped in alcohol or a 10 percent bleach solution between cuts.
Shrubs which have become dense with branches can be reinvigorated by pruning out dead stems and cutting out the oldest third of the main stems (those in the center of the plant) back to 4 to 6 inches above the ground. This will allow more light into the center of the plant, triggering new shoot to grow. Some of the new stems should also be removed, so that the remaining new stems will have room to grow. Shrubs which benefit from thinning are burning bush, honeysuckle, ninebark and sumac.
Some shrubs are fast growing and can become enormous unless kept in control. Depending on how large they are, these fast growers can be completely cut down to 4 to 6 inches each spring. These include barberry, purpleleaf sandcherry, late blooming spirea, potentilla, and the clematis which grow in our zone 3 area. Shrubs like the red twigged dogwood and the flame willow, which have a bright red and orange colored branches, need to be cut down to 4 to 6 inches at least every third year to maintain their bright colored stems.
Trees and shrubs which bloom early in the growing season have buds which were set last fall. If they are pruned at this time, will not bloom this year. If they need pruning these should be pruned after they have bloomed this spring. This would include lilac, chokecherry, flowering plum or cherry, viburnum, Juneberry and bridal wreath spirea.
Trees such as maples, (late winter is the time these trees are being tapped for making syrup) including boxelder, butternut, walnut, birch and its relatives, ironwood and blue beech, have free flowing sap that "bleeds" this time of the year. Pruning will not harm them, but the bleeding is unattractive. To prevent bleeding, these can be pruned after the tree leaves have fully expanded in late spring or early summer.
If pruning makes you nervous, remember that shrubs and trees are forgiving of a less than perfect job of pruning. Maybe the plant will look funny or in some cases may not flower this year, but pruning rarely kills a plant, it will live to recover and grow and bloom again.