Why Prune? The question which is often asked is why pruning should be needed in the garden, as it does not occur in nature; however, this is not absolutely true. Many tree species will shed twigs in their natural habitat (a process known as abscission), and many other factors in a natural environment--readily available light or shade, browsing mammals, soil type, microclimates, weather conditions--affect the growth of plants. In nature, when a tree or shrub is left to its own devices and not interfered with by secateurs (hand pruner or loppers) or the saw, the resulting form and habit does not always highlight the special ornamental attributes of the species or improve the longevity and health of the specimen. Growth may be typical of the species, but under natural conditions, plants are often found in balanced ecological communities and in direct competition with other, often larger plants. The larger plants frequently overpower the weaker, which will die unless they adapt to these conditions. This is not so in the garden, where the weaker plants may be protected by the gardener''s pruning the stronger subjects to restrict their overall size, be they trees or shrubs. As they grow toward maturity, many trees and shrubs accumulate dead twigs and branches; these are best removed, as they are unsightly and may hinder the development of the plant or harbour harmful pests and diseases. Diseased wood should also be cut out during any pruning operation: one of the golden rules of pruning (before any pruning for form is carried out on a plant) is to remove the four Ds--dead, dying, diseased, and damaged.

Then formative pruning can begin with the pruner knowing what living material is left to be used as a framework. Most plantings are made with a definite type of tree or shrub, which from experience is considered the most suitable form of the particular species or variety. Their training to these forms often involves the adoption of a pruning system that may take several years to complete. The need for these forms has been universally recognized for generations, and British Standards (BS) and American National Standards Institute (ANSI) publications lay down very definite sizes and types for the nursery stock of many common species and varieties. In many cases shrubs grown for their floral display are special varieties or cultivars, which have flowers distinct from the species (e.g., they are larger, or differently coloured) and which do not occur under natural conditions. Annual pruning is a necessary part of their cultivation if the required standards of growth and flowering are to be maintained.

Without it and a complementary feeding and watering regimen, growth may be weak and the flowers small, though in some cases, depending on the genus (e.g., Rhododendron , Lavandula , Rosa ), all that is needed is the systematic removal of seedheads or fruits. Some trees and shrubs require regular, annual formal pruning to stimulate flowering spurs for the production of fruit. Only with good pruning and training can the form and beauty of trees and shrubs in summer and winter be fully realized. Good training and growth in particular show up very plainly with deciduous subjects in winter. A well-balanced plant improves most surroundings and helps to provide a restful scene for the mind and eye, but a badly mutilated tree or shrub is depressing and, in a modern urban setting, may be seen by thousands. Pruners must have a thorough knowledge and understanding of the attributes, growth, and flowering habits of the plants they are pruning and of the effects likely to be produced by the operation.

So the questions that we pruners must ask ourselves before we even attempt to carry out any form of pruning are these: what are we trying to achieve? and what do we want to gain from pruning? If we don''t know why we are pruning and what we are expecting, then we will be unable to identify the type of pruning that needs to be done, and the end result will most likely be the wrong outcome--a ruined plant and a waste of our valuable time that could have been better spent in the garden. The main reasons and objectives for pruning are as follows: To develop a strong framework for the future (formative pruning). To continue to develop a strong framework and leader (corrective formative pruning). To maintain or improve flower display and fruit production. To restrict plant growth, including correcting a plant''s size or improving its balance. To remove the four Ds: dead, dying, diseased, and damaged wood--all of which can be dangerous--for safety reasons and disease prevention.