Pruning
Core concepts
Pruning is deliberate wounding with a purpose. Work with the branch collar and branch bark ridge: the three-cut method prevents bark tearing on heavy limbs, and the final cut leaves the collar intact - flush cuts remove the tree's own barrier zone. Know the ANSI A300 pruning types (clean, thin, raise, reduce, structural, restore, crown reduction, pollarding, espalier) and match cuts to objectives. Large cuts close slowly and decay more often; retained branches should be at least one-half (ideally two-thirds) the diameter of the removed limb so a sound defense zone remains. Structural pruning of young trees - subordinating co-dominant stems and included bark - prevents more risk than corrective work on mature trees.
Traps
- 'Cut flush so it heals' and 'paint the wound' - both are discouraged.
- Topping as height control: it forces vigorous sprouts and decay.
- Removing more than about 25% of live crown in one season, less for stressed trees.
- Pruning at the wrong time for wilt-prone species (oaks where oak wilt occurs) or heavy bleeders (maple, birch, walnut) in late winter–spring.
- Lion-tailing, which shifts weight to branch ends and invites failure.
Rule of thumb
If the limb to be removed exceeds roughly half the diameter of the stem it attaches to, make a reduction cut to a lateral that can assume the terminal role rather than a removal cut.