Easy pruning PLANTS THAT ‘BLEED’
Sap rises early in plants such as acers, laburnum and birch, so December is the last chance to prune them
Plants naturally leak a little sap after pruning. In fact, it helps with the healing process, seals the wound and prevents diseases entering. But how much sap plants ‘bleed’ depends on when they’re pruned, which is why deciduous trees and shrubs need pruning in winter when they’re dormant. Leave pruning until spring and the rising sap will ‘bleed’ from the cuts. This is unsightly and can also lead to a loss of vigour and potentially the death of the plant. December is the last chance to prune plants whose sap rises early, such as acers (Japanese maples), walnuts, grape vines, limes (tilia), laburnum, magnolia, hornbeam and birch.
How to do it
l Use clean, sharp secateurs or loppers. If branches are thicker than your thumb, use a pruning saw. l Remove the three Ds. Assess the tree and remove any dead, diseased or damaged branches, which can become a source of infection. Cut back to just above a healthy bud or set of buds. Choose an outward-facing bud to encourage the tree to form an open habit, preventing the centre from becoming too congested. l Remove crossing stems. Next remove any branches that are crossing, to stop them rubbing against each other, which causes wounds to develop. l Take off low branches. If you want to ‘lift’ the crown, remove lower branches close to the trunk. l Make an undercut. Pruning large branches can tear and damage the trunk. To avoid this, make an undercut about 20-30cm (8-12in) away from the trunk. Then make a cut from above to remove the branch, leaving a stub. Remove the stub by sawing almost flush to the branch or trunk.