One of the most frequent questions asked of gardening experts is when – and how – to prune plants and trees. Now that there have been good autumn rainfalls and growth has resumed in the garden, tidying up is in order to give some direction to the way plants grow over the winter. Some of the main reasons for pruning are to get rid of the dead or diseased parts of the plant, branches growing inward, weak or straggly branches, as well as improving air circulation around the plant in hot climates. Shrubs – particularly Mediterranean low-growing maquis plants – that are not clipped will become leggy and sparse. Pruning them into a compact shape will help them to grow more thickly. Pruning is also done to make a plant more productive – for example, where fruit only appears on new growth, the old branches must be cut back each year to ensure the tree bears a new crop the next. (The same applies to flowers, of course.) Some roses, for example, only appear on new growth, but on other varieties they grow on the older parts of the plant, hence the confusion among the uninitiated. Pruning can also allow you to choose one main trunk, where double trunks are forming and to keep a tidy shape. But beware: According to many experienced gardeners, the rule that seems to apply is: When in doubt – don’t. In most cases it is apparently better not to prune than to do it incorrectly. After all, in nature, plants go for years with little or no pruning. «No gardener should feel obliged to prune without a reason,» says Heidi Gildemeister in her classic book «Mediterranean Gardening: A Waterwise Approach.» «Keep a close watch and perform surgery at a sensible time, but have one major assessment in autumn after flowering, eyeing up the different shapes and sizes, gauging the proportions,» writes Patti Baron in «Create a Mediterranean Garden.» Common sense As for where and how to cut, the best way to learn is to watch an experienced gardener but, failing that, there are several good books of instructions – look for ones with clear illustrations of where to make the cut. Instructions in gardening manuals for milder climates do not always apply to the Mediterranean plants, but the general principles are much the same. Once you determine the objectives and learn a few basic principles, pruning is primarily a matter of common sense. As for technique, first remove all dead, broken, diseased or problem limbs by cutting them at the point of origin. Often, removing this material is enough to open up the top of the plant to allow light in so that no further pruning is necessary. If you want to train a plant into a certain shape, cut back lateral branches. After the necessary cuts have been made, stand back and take a look at your work before getting carried away with the secateurs. To properly train a plant, one should understand its natural growth habit. Improper pruning cuts cause unnecessary injury and tear the bark. Flush cuts (right up against the bark of the main branch) injure tissues and can result in decay. Stub cuts (leaving a short stub on the main trunk) prevent wounds from closing quickly and can provide entry to disease. There are several consequences of not pruning at all. These include the development of low aggressive limbs, weak co-dominant stems and defects such the accumulation of dead branches. To conclude with some words of wisdom from Gildemeister: «A garden changes constantly. Plants grow in unexpected directions, seldom stay within assigned boundaries. Over the usually short winter, decide which plant has precedence over the other, evaluate horizontals and verticals. Taking back one plant to allow another to expand is continuous. Giving each sufficient space is one of the aims of a winter cleanup.» Rhythms of nature Those who want to prune in line with the rhythms of nature should consult the Biodynamic Sowing and Planting Calendar 2006, which shows optimum days for sowing, pruning and harvesting various plant crops. The 2006 calendar, compiled by Matthias and Maria Thun, is based on over 40 years of research and experience. It is available from the Soil Association (Bristol House, 40-56 Victoria Street, Bristol, BS1 6BY, UK, tel 0044117.314.5000, e-mail [email protected]).