Colorado State University Extension recommends mowing all Colorado lawn species at 2.5 to 3 inches, never below 2 inches, and removing no more than one-third of the blade at any one mowing. In late spring that often means mowing every 4–7 days; in mid-summer, growth slows and weekly is usually enough.
The 2.5–3 inch rule
Taller grass shades the soil, holds moisture, crowds out weeds and grows deeper roots. CSU Extension’s guidance is a consistent 2.5 to 3 inches through the season. You don’t need to cut lower in late summer or fall. Mowing below 2 inches makes lawns less drought tolerant and more prone to weeds, insects and disease.
The one-third rule
Never remove more than one-third of the grass height in a single mow. If you mow at 3 inches, cut when the grass reaches about 4.5 inches. If rain or a vacation lets it get too tall, raise the mower, cut, then come back a few days later at the normal height.
How often to mow
- May–June: peak growth. Weekly at minimum, sometimes more.
- July–August: heat slows growth; weekly or bi-weekly depending on water.
- September–October: growth picks up again; back to weekly.
This is why most of our customers choose weekly mowing during the growing season.
Bag or mulch the clippings?
Mulching is usually better: clippings break down fast, return nitrogen to the soil and, according to CSU Extension, do not cause thatch. Bag when the grass got too long, when there’s disease, or for a cleaner look before an event.
Sharp blades and clean edges
Dull blades tear grass, leaving brown, frayed tips. Crisp edging along sidewalks and driveways and blowing clippings off hard surfaces are what make a lawn look professionally maintained, and it’s what HOAs notice.
Frequently asked questions
Is it bad to cut grass really short in Colorado?
Yes. Cutting below 2 inches stresses cool-season grasses, reduces drought tolerance and invites weeds. Stick to 2.5–3 inches.
Should I mow shorter for the last mow of the season?
CSU Extension says there’s no need to mow shorter in late summer or fall. Keep a consistent height.
How often should a lawn be mowed in Fort Collins?
Weekly during May–June and September, and weekly or bi-weekly in mid-summer depending on growth and watering.