Crucial cutbacks

It's time to finish your winter pruning. Monty shares his advice on the key plants to cut back this month and why this is an important job to get done

When the last leaf has fallen and bare branches are revealed but the sky is clear and dry then it’s the perfect time for winter pruning. This is a job that best fits into the horticultural no man’s land of January and February when the soil is resistant to nurture and all but the earliest and hardiest plants are still hunkered down against the cold to come. The clue, of course, is in the name. Winter pruning is done in the bleakest part of mid-winter for good reasons.

Although it can start at any time from November and continue until the middle of March, I have a basic rule for my timing of winter pruning: I do not begin until the leaves have fallen and I try to get it done before the leaves start to reappear.

Three main reasons for pruning are: to restrict growth, to promote growth, and to curtail or cure damage from injury or disease. Whatever the desired effect is, you have to cut and it is vital you do this with as sharp an instruments possible, for all the obvious reasons, not least that it is easier. As for the horticultural reasons for winter pruning, it is necessary to know something about how plants store and use their resources. In deciduous trees and shrubs, energy is stored in the roots over winter. As the leaves grow in spring, energy shifts to the leaves and stems where it is used.

Boosting vigour

The fewer stems and leaves there are in spring, the more food is available to them and they will react with a huge increase in vigour and size. For example, I have purple hazel Corylus avellana Purpurea’) in the Jewel Garden that I reduce to just four or five stems every February and prune to the ground every three or four years. The result is enormous purple leaves twice the size of those on the large, unpruned hazel in the Spring Garden.