- Low limbing- Removing the bottom limbs of a tree in order to establish clearance heights that meet City Code or provide visual clearance. Also called crown raising. Trees should not be raised more than a foot or two during one pruning cycle, and a large number of branches should never be removed at one time.
- Sucker pruning- Clipping the suckers that grow from the base of the tree. This can be done at any time of the year and should be done before the suckers get bigger than ¼-1/2 inch.
- Deadwooding- Removing dead branches from a tree. This can be done at any time of the year but is not necessary unless the dead branch becomes a hazard.
- Thinning- Pruning branches from a tree for aesthetic purposes. Some thinning is done to reduce wind resistance; however, this is not really necessary because trees often need their entire branch structure to support each individual branch. Thinning should be done in the winter, although limited thinning can be done in the spring. No more than 20-25% of the canopy should be removed during one pruning cycle.
- Through-pruning- Also called Y-pruning, this practice is performed by utility companies to train trees to grow around high-voltage wires to give the wires at least 10’ of clearance from the tree. Only utility arborists should prune trees around high-voltage wires.
- Topiary- Deliberately pruning trees into fanciful shapes. Topiary pruning is usually performed on evergreen tree species.
- Pollarding- Frequent pruning of the upper branches of a tree to keep the tree at a consistent height and promote dense small branch growth. Pollarding can have similar consequences as topping and is generally discouraged.
- Topping- The destructive and obsolete pruning practice of cutting back large branches to stubs. You should never top trees! Topping is not allowed in the City of Portland and could could lead to fines or mandatory removal and replanting of topped trees. Topping cuts prevent wound closure, leading to decay and weakly attached new branches.
phone: (503) 823-TREE (8733)
1900 SW 4th Avenue, Portland, OR 97201