The basics of pruning
Make sure you have the right tools, and that they are clean and sharp so that any cuts you make will be smooth. Ragged cuts will encourage fungal attack and subsequent decay. A good pair of secateurs will cut branches up to 1cm thick; above this, use loppers – those long-handled pruning shears. A folding pruning saw will be handy for stems that are bigger than 3cm thick (it cuts on the ‘pull’ stroke, unlike a carpenter’s saw, which cuts on the ‘push’ stroke). A pair of shears will be necessary for hedge and topiary clipping.
Keep your blades clean! Rub them regularly with emery paper to remove dried sap, which will cause them to stick. If you have been cutting out diseased material, wash them in disinfectant before oiling them ready for use next time.
Above all, have in mind what you are aiming to achieve before you start, and an understanding of the consequences of the removal of each particular stem. Stand back after every two or three cuts and eye up the plant. That will help you to produce a shapely plant, which will grow in the direction you require and produce the shoots you want to encourage.
If you are in any doubt at all, restrict your pruning to the three Ds: remove dead, diseased and damaged stems, and leave the rest alone.
As a general rule, remember the old adage: “Growth follows the knife.” If you cut a stem ‘hard back’ you will, in most cases, encourage vigorous growth. If that is what you want (in the case of coloured-stemmed dogwoods, which are pruned back to ground level in spring, for instance) all well and good. But consider, instead, whether it would be better simply to thin out a plant’s stems and maybe remove just a few centimetres from the shoot tips to keep it shapely without encouraging vigorous growth.