How to prevent crabgrass: timing is everything
Crabgrass isn't hard to beat — it's just unforgiving about timing. It's an annual: every plant you see grew from seed this year, which means stopping the seed wins the war.
The soil temperature rule
Crabgrass germinates when soil hits roughly 55°F for several consecutive days — in Chicagoland that's typically mid-April, often tracking when forsythia blooms fade. Pre-emergent herbicide has to be down before then; applied after germination, it does nothing. Texans, your window is earlier — late February into March.
Your real defense is density
Crabgrass invades thin, scalped, sun-baked turf. Three habits starve it of opportunity:
- Mow tall. A 3-inch canopy shades soil enough to block most germination — see our height guide
- Water deep, not daily. Shallow watering favors shallow-rooted weeds (the watering guide has the routine)
- Overseed thin areas in fall so there's no bare soil come spring — here's the overseeding playbook
Already up?
Small plants can be pulled (they're shallow-rooted) or spot-treated with a post-emergent labeled for crabgrass. Big August plants are honestly best left to die at frost — focus on a thick fall overseed so next spring starts differently.
Consistent tall mowing is the part Homigo handles automatically — every visit cuts at the right height for the season, which quietly does most of your weed control for you.