Introduction to Practical Pruning
To prune or not to prune? This is a question that always seems to face gardeners. Most feel they ought, but are not sure why or how. It is accepted practice for apple trees, and in the rose garden, but rather haphazard elsewhere. Too often it is only performed when a shrub or tree begins to encroach on its neighbour, a path or a building.
Pruning is often looked upon as the answer to make a barren tree fruitful. Carried out correctly, it will – eventually! But remember, years of neglect cannot be rectified in one season. Further, the pruner who cuts because he thinks he ought, but does not know how, often finishes up with no flower at all, due to the operation being carried out at the wrong time of year, or through cutting too severely.
Some gardeners are obsessed by tidiness and formality, wanting their trees and shrubs to be like smart soldiers on parade. They are lopped to a standard height, and are cut back to a predetermined size and shape. Very often all identical. As spring advances, the gardener becomes distraught for he has not allowed for the different angles or rates of growth that now reduce his parade-ground effect to a shambles.
What then is pinning? Why does one prune? When? How? First, the act ofcan be described as the removal of a part or parts of a woody plant by man for a specific purpose. The reasons for pruning are:
1. To train the plant.
2. To maintain plant health.
3. To obtain a balance between growth and dowering.
4. To improve the quality of, fruit, foliage or stems.
5. To restrict growth.
A woody plant will come into cropping earlier if it is allowed to grow naturally. Pruning delays flowering, but in the early years it ensures a framework of strong well-spaced branches, later to produce flowers and fruit. A tree of desired size and shape can be fashioned which is not only well balanced and delightful to the eye, but carries flowers or fruits where they can be easily seen and reached. Building up of the initial framework makes for easier management of the tree, shrub or climber in later years.
MAINTENANCE OF PLANT HEALTH
A beautiful tree is a healthy one! Control of pests and diseases is essential and it is easiest if the cause of these afflictions can be removed as early as possible. Pruning is one way in which this can be done. Routine spraying can control pests and some diseases in shrubs and young trees, but it becomes impracticable – if not impossible – on large trees. Pruning becomes the only feasible method of control.
Most diseases that attack trees enter through wounds, and spread via the conducting tissue, killing off branches as they extend their hold. If disease reaches the trunk, death usually results. The disease organism travels beyond the wood it has killed off, and its presence in apparently healthy wood can be detected by a brown interior staining. When diseased wood is being removed always cut back to sound wood, that is, wood where there is no staining.
Dead wood is always unsightly and likely to break off, possibly causing damage to healthy parts. It is the breeding ground for disease which can spread from the dead wood to the live (for example, coral spot). Obviously, dead wood should be removed, generally, at any time of year, but particularly at the main pruning time.
BALANCE BETWEEN GROWTH AND FLOWERS
Pruning in the early years should be sufficient only for training. Once a tree or shrub has come into full flowering, shoot production will decline until at maturity very little annual growth is being added.
Remember that a relatively young plant, if growing too vigorously, will produce fewer flowers. Light pruning will therefore slow down the rate of growth. A heavy pruning, however, can delay — or even prevent – flowering.
In a mature plant it is the young wood which produces leaves. It is therefore desirable to encourage a woody plant to maintain the regular production of young wood, and this is best done by regular pruning.
IMPROVING THE ORNAMENTAL QUALITY
The more flowers and fruit a plant produces, the smaller the individual blooms and fruits become, as can be witnessed on an unpruned rose bush or fruit tree. Pruning reduces the amount of wood and so diverts energy into the production of larger, though fewer, flowers and/or fruit. For example, the length of flower spikes on an unpruneddavidii (butterfly bush) may be 10 cm (4 in), but can exceed 30 cm (12 in) on one that has been pruned.
Leaves are produced only on current season’s growth. The more vigorous, this is, the larger will be the leaves, and in plants with coloured foliage, the more intense will be the colouring. Shrubs grown for their decorative leaves, (summer or autumn tints, variegated, coloured or dissected), are pruned hard each year.
Some deciduous shrubs have coloured barks which are especially delightful in winter when there is little colour elsewhere. The best hues are produced on young stems with the greatest length, and this can only result from hard annual pruning.
RESTRICTION OF GROWTH
If trees and shrubs are left to develop naturally, they grow bigger and bigger, often becoming an embarrassment where space is restricted. Pruning, therefore, becomes necessary to keep them within bounds.
OTHER FORMS OF PRUNING
There are some jobs carried out in a garden which are also forms of pruning, although they are not always recognized as such.
□ The cutting of blooms from woody plants for indoor flower arranging is a type of pruning. □ Trimming hedges is restrictive pruning applied to a row of shrubs.
□ Topiary – the clipping of bushes to bizarre shapes – and pleaching (used to make living screens or arches), are both combinations of training and restrictive pruning.