Correct pruning is one of the single most significant factors determining whether a tree or bush grows well or not. Pruning, or to be more precise, its incorrect application, is also very often responsible for causing damage, unsatisfactory growth, and even early death in plants. Although it’s not possible to learn the art of pruning in practical terms by reading an article or two, it is nonetheless realistic to expect to understand the basic principles behind it. Or put simply, what to do and what not to do.
Timing
A basic rule is that plants sensitive to cold should never be pruned until every possibility of frost has passed for the year. The reason is that the pruning wounds do not heal properly, and become a source of bacterial and fungal infection. On the other hand, deciduous plants, that is those that have evolved in cold-temperate climates, should be pruned during their dormant season (i.e. the winter) but not in the spring, as at that time of year, pruning causes the sap in the plan’s tissues to “bleed” out of the plant.
While in cold regions, pruning is carried out at the beginning of the winter, in mild winter climates, where the minimum temperatures reach say -4c; the pruning of deciduous plants should be delayed until the end of the winter. For an explanation click on the link below and on the “Articles” page scroll down to
- Pruning in the autumn – What you should and should not do.
- Pruning trees and shrubs – one mistake you must not make.
Quantity
It is a big mistake to remove too much material from a particular specimen at any one time. One rough guide determines that no more than one third of the total volume of branches should be pruned. I personally set a maximum amount at far less than that. Remember that excessive pruning, even at a time when a plant is dormant, seriously affects the plant’s energy level. If a lot of material is to be cut away, then the pruning should be staggered over two years or more.
Quality
The nature and quality of the pruning cuts affects the ability of the tree or shrub to overcome the wounds inflicted on it. There is a quaint view amongst some ill-informed gardeners that pruning is “good” for plants. It is about as good for plants as surgery is for people. It should be carried out therefore with the clear awareness that every wound is a source of infection. Admittedly, woody plants posses their own “defense mechanisms” which isolate the rot and decay which develop from the wounds caused by pruning, but there is a limit to how far this is possible. Here then are some guidelines.
- The size of the cut should be as small as possible in relation to the width of the branch or trunk on which the wound is to be made.
- Small stubs should not be left, as these become subject to bacterial and fungal attack, which can proceed into the main trunk or branch itself. On the other hand, cuts that are made too flush with the trunk, while appearing to have calloused over, can also cause rot to develop behind them and therefore within the trunk. It is important therefore to make the cut, just beyond the joint between the branch which is to be removed and the trunk to which it is attached.
- Pruning saws must be as sharp as possible, in order to ensure that the cut is as “clean” as possible. A jagged, torn cut on the other hand, has a total wound surface area that grows exponentially compared to a clean cut, thereby reducing the tree’s capacity to isolate the infection, and consequently, increasing the chance of rot and decay developing.