Crown raising
Also called: limbing up, raising the canopy, crown lifting, canopy raising, elevating a tree, removing lower branches
Removing a tree's lowest branches to lift the bottom of the canopy — typically to 8 feet over a lawn, 10–12 over a walk or driveway, and 14 over a street — for clearance and sightlines. Done gradually, keeping the live crown at least two-thirds of the tree's height.
Every mature tree on a street or a lawn has been raised: the lower limbs that a young tree carries to the ground were removed over years, so that people, mowers, cars and roofs can pass beneath. It’s the most common pruning operation there is, and the one homeowners do most — the lowest limbs are the ones in reach, and taking them off is satisfying. The cut is the same collar cut as any other; the decision is which limbs and how far.
The guideline arborists use is a two-thirds rule: after raising, the live crown should still occupy at least two-thirds of the tree’s total height. A trunk with foliage only in its top third is a lever with all the sail at the tip, it’s more prone to sunscald where bark that was shaded is now exposed, and it tapers less — the lower limbs are what thicken the trunk. Raise a young tree a little each year rather than all at once, leaving temporary lower branches for a few seasons to build the trunk. On a mature tree, raise only as far as the clearance actually requires, and count the removed limbs toward the yearly quarter of the live crown.
Clearance targets are practical: 8 feet over a lawn for a mower and a person; 10–12 over a driveway or walk; 14–16 over a street (most cities have an ordinance); and enough over a roof that limbs don’t touch in wind, usually 6–10 feet, which is where a crew’s rigging starts. The DIY guide puts raising after the deadwood and before any thinning; the cost page prices it inside every tier.