Although some plants can be pruned at almost any time of the year, in general this is far from being the case and often timing is critical if the desired result is to be achieved.
The main pruning period for many plants, including roses, soft fruits, and many tree fruits, is the dormant season, from late autumn to early spring.
However, winter pruning stimulates growth whereas summer pruning checks it.
Most of the pruning to form the spur systems of restricted forms of fruit trees, such as cordons and espaliers, is carried out in summer to avoid promoting unmanageable growth.
The full ornamental potential of many plants can only be realised by pruning at an appropriate time and must take account of the age of the wood that bears flowers, the most decorative foliage, or the most vividly coloured stems.
Many shrubs that flower in the spring, do so most prolifically on one-year-old wood.
Cutting out the oldest wood immediately after flowering will encourage the development of replacement shoots that will flower the following year.
Shrubs and climbers that flower on the current seasons wood are best pruned in early spring, the previous years wood being cut back to a low framework of branches.
In the case of some plants that are susceptible to particular diseases, the risk of infection can be reduced by pruning when they are least vulnerable.
Silverleaf is a serious fungal disease of plums and other stone fruits and also of some ornamentals.
The windborne spores, which gain entry to the plant through fresh wounds, including pruning cuts, are released by the fruiting bodies of the fungus from early autumn to late spring.
Summer pruning greatly lessens the risk of infection, especially if a wound paint is applied soon as the cuts have been made.