Robot mowers and trees: canopy, roots, and signal dropouts

Canopy is the problem, not the trunk

A mower steers around a trunk easily. What it cannot do is receive satellite signals through a full canopy, and in summer a mature oak or maple blocks most of the sky beneath it. Owners with RTK mowers under trees report the mower stopping, wandering, or leaving uncut strips exactly where the shade is deepest. The advisor measures canopy over the lawn from imagery and flags any wireless mower once it passes about 15 percent.

Roots, drops and acorns

Surface roots trip small-wheeled mowers and dull blades. Fallen fruit, nuts and sticks jam blade discs. If your trees drop a lot, a mower with larger wheels and a raised blade deck copes better, and mowing a little more often than the manufacturer suggests keeps debris small enough to pass.

What works under heavy cover

Boundary wire, without exception, and vision mowers in most cases. If you are set on RTK, look for models with vision or inertial backup that keep mowing through short dropouts, and mount the base station where it sees clear sky, often the roof line. Excluding the deepest shade as a no-go zone and trimming there by hand is the honest fallback.

Season matters. A lawn that scans clean in March can lose its signal in July when the canopy fills in. If you are buying in spring, judge the cover by last summer's imagery or by standing under the trees and looking up: if you see mostly leaves, plan for wire or vision.

How the advisor measures your trees

Yard Truth estimates tree cover over the lawn from satellite imagery of your parcel and reports it as a percentage. Under 15 percent, every guidance system is in play. Between 15 and 35 percent, RTK mowers without a backup system are marked conditional and models with vision or inertial fallback move up. Over 35 percent, wire and vision mowers lead and RTK-only models are marked poor. You can correct the figure if the imagery is old or the trees have come down.