Author: Dianne DeLongchamps
What mowing height prevents heat stress in a Colorado summer?
Three inches is our floor. In July and August, we call for 3.5. We never recommend mowing below 3 inches here. The fescue and Kentucky bluegrass that make up most Fort Collins, Windsor, and Timnath lawns should not be cut low under any circumstance.
Clean Air Lawn Care is a treatment company, custom organic fertilizers and organic soil builders, non-toxic, plus bio-based weed control including Moose Juice, our own blend. Mowing height is the first thing Luke brings up on a walkthrough: it’s free, and it changes more than anything we apply. Pair 3 inches with 1 to 2 inches of water a week across two to three deep waterings, 2 inches from mid-July to mid-August.
Where does the 3-inch number come from?
CSU Extension publishes two different ranges.
- CSU PlantTalk 1515: “The preferred height of Colorado turfgrass species is two inches to three and one half inches.”
- CSU Fact Sheet 7.202: “The minimum height for any lawn is 2 inches. The preferred mowing height for all Colorado species is 2.5 to 3 inches.”
The overlap is 2.5 to 3 inches. Our 3-inch floor is our own standard, the top of CSU’s preferred band, inside PlantTalk’s wider range.
CSU is clear about going low. PlantTalk 1515: mowing under two inches “can reduce drought and heat tolerance, and cause a higher incidence of insect, disease and weed pest problems.” CSU’s Master Gardener turf guidance adds the reason, “due to shallow rooting and reduced photosynthesis”, and notes it “encouraged weed invasion.”
Why can’t I cut my lawn as short as a golf course?
A tight, striped, carpet-short lawn looks incredible. It also isn’t your grass.
Golf greens are usually creeping bentgrass, or bentgrass mixed with annual bluegrass. That’s done with reel mowers, which cut with a scissoring action against a bedknife and, per University of Minnesota Extension, “provide the finest quality of cut available.” UMN also notes reel mowers “are not well adapted for use in higher heights of cut.”
The most typical mower found in a garage is a rotary. UMN: it “cuts the grass by impact, similar to the way a machete works,” giving “a rougher, more uneven cut.” Different plant, different machine. Cutting Kentucky bluegrass short with a rotary mower in a Front Range summer gives you a thin, scorched, weed-friendly lawn by August.
What does taller grass do for my lawn?
It shades its own soil, and it blocks crabgrass. University of Minnesota Extension is specific: “Raising mowing heights to at least 3 inches reduces the amount of sunlight that reaches the soil, reducing crabgrass seed germination.” That’s weed control you don’t have to buy, at exactly our height.
It supports deeper roots. UMass Extension turf specialists: “The root systems of grasses generally become shorter and less prolific as cutting height decreases, resulting in a need for more frequent watering and fertilization.”
It buys margin going into heat. A lawn at 3.5 inches has some reserve. One at 2 inches has none.
How much grass can I cut at one time?
Never remove more than a third of the grass height in one pass. CSU 7.202: “Mow the turf often enough so no more than 1/3 of the grass height is removed at any single mowing.”
From UMN: to maintain a 3-inch lawn, mow before the grass reaches 4.5 inches.
If it’s six inches tall, don’t drop it to three in one go. Two passes a few days apart.
What should my week-to-week mowing schedule look like?
- 3 inches minimum, 3.5 through July and August.
- Sharp blade. CSU’s interval: “Sharpen blades after every third mowing, or, at the least, once a month.” A dull blade tears, and torn tips brown out in a day.
- Mow more often, not shorter. CSU puts the interval at “four to ten days between mowing” depending on growth. CSU’s own summary: “keep mowing ’til’ the lawn stops growing.”
- Leave the clippings. PlantTalk 1515: “Clippings break down quickly, which allows nitrogen and other nutrients to be recycled.” And 7.202: “Grass clippings do not contribute to thatch accumulation.”
- Don’t mow a wilted lawn. If the grass has that dull gray-blue cast or blades are folding, wait for a cooler morning.
Is electric lawn equipment quieter than gas?
Everything we run is 100% electric and solar-charged. No exhaust in a yard we’re building soil biology in.
On noise, UGA Extension: “Battery powered lawn equipment tends to be quieter than gas powered equipment.” Quieter, yes. Silent, no. See our electric lawn mowing service page for more information on how we mow lawns.
Luke is on lawns across Fort Collins, Windsor, and Timnath most days of the week, and mower height is the thing he’d change first on almost every struggling yard he walks onto. Free, ten seconds, and usually the difference between a lawn that shrugs off a heat wave and one that spends September recovering. Set the deck at 3. Go to 3.5 in July and August.
Clean Air Lawn Care Northern Colorado is owned by Dianne, Paul, and Luke DeLongchamps — a family business serving Fort Collins, Windsor, and Timnath with organic lawn treatments and solar-powered electric equipment.
