The Scalping Problem
It's a common instinct — cut the grass short so you don't have to mow as often. But cutting more than one-third of the grass blade in a single mow stresses the plant, depletes energy reserves stored in the leaf, and exposes the soil to direct sunlight. The result: dried-out soil, more weeds, and weaker roots.
The One-Third Rule
Experienced lawn care professionals follow the one-third rule: never remove more than one-third of the blade length in a single cut. For most cool-season grasses common in Ontario — Kentucky bluegrass, fescues, and ryegrass — the ideal maintained height is between 2.5 and 3.5 inches.
Taller grass shades the soil, retaining moisture and making it harder for weed seeds to germinate. It also encourages deeper root development, which means grass stays greener longer during dry spells.
Seasonal Adjustments
Height isn't a set-it-and-forget-it number. In the heat of summer, raising the cutting deck slightly helps the lawn cope with stress. In spring and fall — the primary growth seasons in the Durham Region — regular cutting at proper height keeps the turf dense and competitive.
Blade Sharpness Matters Too
A dull mower blade tears the grass rather than cutting it cleanly. Torn grass tips turn brown and create entry points for disease. Sharp blades produce clean cuts that heal quickly and keep your lawn looking professionally maintained between visits.