Time is now for pruning
While it was a long, cold, old fashioned winter with a lot of snow, spring is once again taking control. However, the long, cold winter only makes us appreciate spring and the impending summer more. The large amount of snow which came before the temperatures became really cold, covered the ground well and should have protected our plants for their long rest. One important task which we should do now before April 1, is to prune our trees and shrubs.
Pruning in late winter, just before bud break and spring growth starts, leaves fresh wounds exposed for only a short length of time before new growth begins and provides the best wound healing process. Pruning which is done during the late fall or cold winter months often results in drying or die-back at the pruning site from the cold temperatures and wind. Another advantage of dormant pruning is that you can see the branches without leaves obscuring the plant structure. You will be able to see dead or dying branches, diseased or injured branches, branches which are too low, and branches which may be crossing and rubbing against each other.
Trees which are especially important to prune before April are oak trees to prevent oak wilt, and apple, flowering crab, mountain ash, hawthorns and shrub cotoneasters to prevent fireblight. If these trees are pruned later in the spring (April, May and June) there is a much greater chance of infection and spread of the bacterial diseases.
Black knot disease in chokecherry and cherry trees is easy to recognize at this time of year. These should be cut back six inches into live healthy wood which is usually evident by the presence of visible buds. Pruning the black knots out will stop the advance of the disease. Whenever you prune, if you wonder if the branch is alive or not, take your pruning shears and gently scrape back the bark.If it is green it is alive; if it is brown it should be pruned. The pruning cut should be just above a live bud.
If you have a red-twigged dogwood, and it suffered from anthracnose (brown spots, or discolored blotches on the leaves, twig die-back, and defoliage of leaves) last summer, now would be a good time to prune out the dead twigs and branches, and thin out the shrub. Anthracnose is cased by wind-borne fungal spores. When the weather is humid and warm for several days, and a shrub has thick foliage, the result is poor air circulation through its branches, and it becomes a prime target for anthracnose. So the shrub needs thinning out, or it may benefit from cutting down all branches to within 3-4 inches of the ground. It will come back nicely.
Early spring bloomers set their flower buds the fall before. If pruned at this time of year, the result will be no blossoms this spring. They should be pruned after they have blossomed this spring so they can set blossom this fall for next spring. These trees and shrubs include: azalea, bridal wreath spirea, chokeberry, chokecherry, clove current, flowering crabapple, flowering plum or cherry, forsythia, bigleaf hydrangea, honeysuckle, juneberry, lilac, ninebark, serviceberry, viburnum and weigela.
Shrubs which are grown primarily for their foliage rather than showy flowers should be pruned now, in the spring when they are still dormant, before growth begins. These include: alpine currant, barberry, buffaloberry, burning bush, butterfly bush, dogwoods, flowering plums, honeysuckle, Peegee Hydrangea, ninebark, peashrub, potentilla, purpleleaf sandcherry, smokebush, spirea (except Bridal Wreath), sumac and Wisteria. Every 4-5 years these shrubs also benefit from being pruned to 6 inches of the ground, specially if they look out of control.
Clematis in our zone 3 should be pruned back to the ground. Hardier shrubs such as late blooming spireas and snowball hydrangeas should be pruned to the first pair of live buds above the ground.
Trees which have free-flowing sap that "bleeds" include all maples, including boxelder, butternut, walnut, birch and it relatives, ironwood and blue beech, can be pruned in late spring after their leaves are fully expanded. The bleeding causes little harm, but is a source for concern for some. However never remove more than 1/4 of the live foliage from a tree.
If a shrub or tree does not fit its surroundings, attempts to prune it severely to proper size and shape often produce disagreeable results; it is better to dig the misfit out and put an appropriate plant in its place. Many new smaller or dwarf trees and shrubs have been developed in recent years to provide a wide selection from which to choose.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.