Young deciduous trees | Mature trees | Conifers | Shrubs | Hard Cutting Back
Young deciduous trees
Pruning trees and shrubs can be quite complicated but there are a few general guidelines to consider. The only essential pruning is the removal of dead, damaged or diseased branches, and even this might not need to be carried out in a natural setting.
Trees have natural shape that should be preserved
Trees and shrubs generally do not need pruning. However, the shape of a tree, or the flowering display of a shrub, can be enhanced by pruning. Carefully observe the plant’s shape and discover its flowering time before attempting pruning.
Mature trees may need considerable pruning for safety reasons if large, heavy limbs pose a hazard. This dangerous and highly skilled work is best left to a qualified, fully insured tree surgeon.
Leave the branch collar intact when pruning
If a small branch has to be removed, to let in light, for example, it should first be cut half way through on the underside, about 45 centimetres from the trunk. This cut prevents the branch tearing away the bark of the trunk. Next, cut through from the top. Finally, cut off the ‘snag’, leaving the all-important branch collar undamaged.
Most conifers are best left unpruned because any pruning more light foliage trimming will tend to spoil their shape, which is the main reason for growing them. If they get too big for their position, take them out completely. ‘Topped’ conifers are an eyesore!
Flowering shrubs generally benefit from a little careful pruning. It helps to maintain a good display of flower and prevents the shrubs getting too big or too dense. The aim is to encourage the replacement of old shoots by new ones, removing the old ones completely, from where they arise on larger branches or from the ground.
Prune spring and early summer flowering shrubs such as forsythia, flowering currant and philadelphus immediately after flowering. Shrubs that flower after the end of July should be pruned in March. These include hydrangea, hypericum and fuchsia.
Very many flowering shrubs need no pruning – rhododendron, camellia, pernettya, witch hazel and magnolia. These can have badly placed branches or over-long branches removed. Make sure that any pruning carried out is to a purpose.
The flowering shrubs that benefit are generally twiggy and bushy with many stems at ground level. Evergreen shrubs are grown for their foliage value and are not pruned usually but they can be reduced in size if necessary.
Hard Cutting Back
Most shrubs can be cut back hard
While careful pruning enhances a tree or shrub, heavy cutting back usually spoils a plant’s shape, at least temporarily, but it might become necessary if a plant has outgrown its space. Before hard cutting back consider removing some shrubs or trees completely from a planting to allow room for the development of the remainder.
The best method of cutting back trees or shrubs is to reduce the number of branches. Completely remove, at source, half of the plant’s branches. Careful selection of the branches for removal will allow the plant to retain its shape. This thinning process may achieve enough size reduction. If not, shorten the remaining branches by one-third or half of their length.
Another method, for shrubs only, is to cut the plant right down to ground level. The cut stumps will sprout again and the shrub will regenerate itself. This rather drastic treatment should be carried out in April and may occasionally cause a shrub to die off.
To actually kill off tree stumps and prevent sprouting, paint the cut surfaces with Roundup. If the tree stem diameter is more than 10 centimetres, drill one hole for each 10 centimetres of diameter of the stump using a bit and brace and place some undiluted Roundup in the holes.