Lawn care is a timing problem
Almost every lawn job has a window when it works brilliantly and a wide stretch of calendar where it wastes money or backfires: pre-emergent after crabgrass sprouts does nothing, September seed in the South cooks, November nitrogen up north feeds snow mold. The windows aren’t secret — they’re just local, anchored to how your climate warms up and shuts down.
This lookup computes them from your town’s NOAA climate normals. The same anchors power our city pages — after a lookup, your location is remembered so every calculator and guide on the site can use it.
The year at a glance
Cool-season lawns (the North and mountains): spring is for pre-emergent and a light feeding; summer is for mowing tall and watering deep; early fall is the main event — aerate, overseed, and feed — and a winterizer feeding closes the year around first frost. Warm-season lawns (the South): everything shifts to the warm half — seed, feed, and aerate from late spring through midsummer, then stop feeding 6–8 weeks before frost and let the lawn go dormant on schedule. State-by-state details live under when to…, and every city’s full calendar is at lawn calendars.
Frequently asked questions
Where do these dates come from?
From NOAA 1991–2020 climate normals: your town’s average last spring frost and first fall frost, measured at the nearest weather station. Each task window is then counted from those two dates using standard university-extension timing rules — e.g. cool-season overseeding lands 45–60 days before the first fall frost.
How accurate is the pre-emergent window?
It’s an honest estimate, not gospel. Crabgrass germination is driven by soil temperature (~55°F at 1–2″ for several days), and frost dates are a proxy for that. The window gets you in the right two-to-three weeks; a soil thermometer or your state extension’s soil temperature map is the precise trigger.
What if I don’t know whether my grass is cool-season or warm-season?
If your lawn stays green through winter and struggles in July heat, it’s cool-season (bluegrass, fescue, ryegrass). If it turns uniformly brown after the first frost and thrives in summer, it’s warm-season (Bermuda, Zoysia, St. Augustine). Our grass type guides have photos and ID cues.
Why does my window differ from the bag or a national article?
Generic advice is written for an “average” climate that almost nobody lives in. The same job can be six weeks apart between Minneapolis and Atlanta. These windows come from your own town’s climate record, which is the whole point.