Make your garden a cut above with some pruning know-how

Is your green thumb itching? It’s too early to get out in your garden, but it’s not too early to expand your gardening knowledge. The St. Albert Botanic Park is offering great tips to help you with your pruning. Be sure to check out their website www.stalbertbotanicpark.com.

Pruning can be very effective in controlling the growth of woody plants, but it doesn’t necessarily apply to all woody species. Evergreen conifers, such as pine, spruce and fir, will develop an attractive mature tree shape, usually pyramidal, that seldom needs any adjusting through pruning. Occasionally, the terminal growing point may become damaged or diseased and sub terminal branches compete for dominance, resulting in formation of two trunks. This alters the overall shape and density of the tree, giving it a “twinned” appearance. Proper pruning procedures can remedy this problem if applied as soon as the original damage is detected.  Other pruning of these conifers should be limited to the removal of dead or damaged branches. To me these kinds of trees are most attractive when their branches are allowed to touch the ground. The removal of lower branches to allow one to mow grass under them or to walk under them destroys their inherent beauty.

On the other hand, deciduous trees and shrubs can benefit greatly from judicious pruning to both train them to a desired shape and density as well as to keep them healthy and productive. This is especially important if flowers and fruit are important. Apple trees, for instance, can be pruned to evenly space the main branches, thus allowing more light and good circulation of air to the fruiting spurs.

Two glaring errors of improper pruning that show up regularly in private gardens and, sometimes in some town plantings as well, is pollarding and shearing. Pollarding is the drastic sawing off of all the main branches of a tree to shorten their length and reduce the height of the tree. This leads to the development of a “rat’s nest” of water sprouts on the stumps or in some cases the death of limbs or the entire tree. These water sprouts develop rapidly into vigorous branches with weak crotches that pose a future safety issue. Also, the tree quickly reaches its original height, negating the reason for pollarding in the first place. Tree height can be reduced or maintained through judicial heading back of upper growth when done over a period of years. An even better approach to this problem would have been to have chosen trees for planting that have a shorter mature height suitable for the particular location. When planting trees, it is important to consider their overall mature height and spread in order to avoid future problems.        

The second common error in pruning is the shearing of shrubs whereby all branches are chopped back giving the shrub a dense, round, ball shape. This destroys the shrub’s natural shape and increases its density to the extent of causing inner and lower branches to die. A much better approach is to head back individual branches to different lengths and to remove weak and crossing branches, i.e., a thinning process. Shearing should be limited to formal hedges. In the case of hedges, individual plants are placed close together and the resulting hedge is sheared once or twice a year to keep it neat and to control its height. With hedges it is important to keep the base wider than the top. This tapered approach allows light to reach the lower branches to keep them healthy and productive.