Pruning that is done by the amateur gardener is carried out to maintain a plant that has been already trained in a nursery. However, many keen gardeners grow shrubs and even trees from cuttings and seed, even though it is better to leave a large tree to the experts, because of the special equipment required and the risks involved. The principles that must guide the gardener when he picks up a pair of secateurs should always be 'a well pruned plant is a beautiful and healthy plant' and 'pruning well carried out should almost be undetectable'.

Trees do not necessarily have to be pruned. The reason for pruning them is to shape or keep a specimen that displays the finest features of a particular species. Any work carried out should be limited to encouraging or assisting the natural development of each plant as it grows from a young tree into a fully grown one and to avoid defects that might turn out to be harmful to the tree.

Shrubs can be pruned to emphasize their ornamental features but it is important to strike a balance between encouraging the production of flowers and allowing the plant to continue to grow and develop. Another objective in pruning is to maintain the characteristic form of each species, encouraging the branches and stems to develop and grow in a way that allows the plant to achieve its natural potential.

Sometimes pruning is needed to encourage the growth of a properly balanced plant. The weakest shoots may need to be cut back hard to one, two or three shoots to stimulate vigorous growth or it may be necessary to reduce by two or three shoots only the most vigorous and strongly growing branches so as not to put too much stress on the plant's other stems.

Pruning is also carried out to maintain the youngest shoots which are the most productive. The last but by no means the least important aim in pruning is to protect the plant's health.

All branches that are dry, diseased, broken or damaged in any way should be removed by cutting into the nearest healthy wood immediately above a well-developed shoot. Smaller branches that are too slender, too thick or that cross in the center of the plant or any that are badly positioned should also be removed by cutting at the base of the young wood but not the main branch from which it is growing.

These actions, which are intended to eliminate possible sources of disease and to maintain an open, regular shape into which sun and air can penetrate freely, should be carried out annually on all plants regardless of when they flower. In areas with a very hot climate this can be the end of summer. In cold areas it is better to wait until the end of winter. Where there is snow it is prudent to anticipate possible damage and in autumn cut the longest braches back or tie them into bundles.

Observation and an understanding of the ways in which a plant grows are useful when deciding if and when to prune. First it is important to check whether the plant flowers on wood grown during the same year as the flowering taking place or on wood that grew in a previous year. This knowledge will dictate the best time to prune.