Many homeowners want a tree made smaller, whether for a view, more light, or peace of mind during windstorms. How the tree is reduced makes all the difference to its long-term health and safety.

What is topping?

Topping cuts the trunk or large limbs back to stubs or to small branches that cannot take over as a leader. It removes a large share of the tree’s leaves at once, leaves big wounds that decay, and triggers a flush of fast, weakly attached sprouts. Within a few years the tree is often taller, denser and more dangerous than before. Most city codes and industry standards prohibit or discourage topping.

What is crown reduction?

Crown reduction makes a tree smaller by cutting branches back to a living side branch (a lateral) that is large enough to take over. Under ANSI A300 standards and many city guidelines, including Bellevue’s, a good rule of thumb is:

• Cut back to a lateral at least one-third the diameter of the branch being removed.
• Remove no more than about one-quarter of the foliage in a single pruning.
• Keep the tree’s natural shape and leave interior foliage in place (no “lion-tailing”).
• Make cuts just outside the branch collar, without stubs or flush cuts.

Why it matters for tree health

Done properly, crown reduction reduces weight at the ends of long limbs, lowers wind load, and can open views, while leaving enough leaves for the tree to stay healthy and close its wounds. Some trees, like bigleaf maple and cottonwood, respond with sprouts, so follow-up maintenance every few years keeps the reduced form.

Pruning in critical areas

If your tree is on a steep slope, near a stream or wetland, or close to a shoreline, even pruning may require city review. In Bellevue, for example, crown reduction that follows the city’s Tree Pruning Guidelines can be reviewed as select vegetation pruning, while other work may need a Vegetation Management Plan. A pruning plan from an arborist describing the techniques and the long-term effects on the tree is often required.

Need help? ABC Herron Tree provides arborist reports, tree risk assessments and permit support in King and Snohomish County. Request a consultation or call 425-293-2443.