There is no practical method for stopping the flow of sap from a bleeding wound, and in most cases, this bleeding is completely harmless. Binding and wrapping the cut is not recommended, as it is better to allow air to reach the wound and let it heal naturally. Wrapping or binding can cause dampness and lack of ventilation, encouraging the development of fungal diseases. We no longer recommend painting pruning cuts with wound paints (such as Arbrex), as this too may trap moisture and promote fungal infection.
Instead, gardeners are advised to check the recommended times for pruning particular trees, shrubs and climbers. This should minimise bleeding.
The following plants are particularly prone to bleeding, so pruning at the correct time will help prevent it.
Acer (maple): Prune Japanese maples (A. palmatum and A. japonicum) after leaf fall but before January; prune snakebark maples (e.g. A. davidii, A. pensylvanicum, A. rufinerve) in late summer.
Betula (birch): Avoid any pruning if possible; otherwise prune late summer to mid-winter.
Carpinus (hornbeam): Prune late summer to mid-winter.
Carya (pecan and hickory): Prune in autumn or early winter.
Juglans (walnut): Prune mid-summer, before mid-winter.
Laburnum: Prune late summer, before mid-winter.
Magnolia (deciduous, spring-flowering types only): Prune early to mid-summer.
Morus (mulberry): Prune from autumn to early winter.
Populus (poplar): Prune late summer or early autumn, except for P. x candicans and its cultivars, which can be pruned in late winter and do not usually bleed.
Sophora: Prune in summer.
Tilia (lime): Prune mid-summer to mid-winter.
Vitis (grape vine – edible and ornamental types): Prune after leaf fall but before Christmas to be safe.
Check individual plants in the book, RHS Pruning & Training, by Christopher Brickell and David Joyce. Available from the RHS Book Shop online.