Timed off your first frost
When to Overseed — by USDA Zone and State
The right week to overseed is set by your first fall freeze, not by the calendar: seed goes down about 6–8 weeks ahead of it, so a lawn in Minnesota seeds in August while one in North Carolina waits until September. Find your zone or state for the dates, then follow the grass-by-grass guide for rate, prep, and watering.
By USDA hardiness zone
Zone 3
Seed July 21 – August 4 — first freeze normally around September 15.
Zone 3 dates →Zone 4
Seed July 31 – August 14 — first freeze normally around September 25.
Zone 4 dates →Zone 5
Seed August 10–24 — first freeze normally around October 5.
Zone 5 dates →Zone 6
Seed August 25 – September 8 — first freeze normally around October 20.
Zone 6 dates →Zone 7
Seed September 6–20 — first freeze normally around November 1.
Zone 7 dates →When is your first freeze?
Every window on this page is worked back from a first freeze covering a wide area. Enter your ZIP for the NOAA freeze normals at the station nearest you, and count your six weeks back from that — free, no signup required.
Free · no signup · NOAA 1991–2020 normals
By state
Worked back from long-term NOAA freeze normals for the cool-season parts of each state, and anchored to the earliest-freezing station rather than averaged across them — a statewide window has to close before the coldest county's freeze, so it runs early for milder areas. Where a state's stations disagree by more than a week, its page names the later window too. States that are entirely warm-season turf aren't listed — overseeding a warm-season lawn for winter color is a different job on a different calendar.
- AlaskaAugust 2–16
- ColoradoAugust 9–23
- ConnecticutAugust 18 – September 1
- DelawareSeptember 6–20
- Washington, D.C.September 22 – October 6
- IdahoAugust 20 – September 3
- IllinoisAugust 21 – September 4
- IndianaAugust 27 – September 10
- IowaAugust 22 – September 5
- KansasSeptember 3–17
- KentuckySeptember 9–23
- MaineAugust 15–29
- MarylandSeptember 3–17
- MassachusettsSeptember 13–27
- MichiganAugust 21 – September 4
- MinnesotaAugust 2–16
- MissouriAugust 28 – September 11
- MontanaAugust 9–23
- NebraskaAugust 16–30
- NevadaAugust 24 – September 7
- New HampshireAugust 19 – September 2
- New JerseySeptember 15–29
- New MexicoSeptember 9–23
- New YorkAugust 15–29
- North CarolinaSeptember 9–23
- North DakotaAugust 4–18
- OhioAugust 29 – September 12
- OklahomaSeptember 14–28
- PennsylvaniaAugust 25 – September 8
- Rhode IslandAugust 30 – September 13
- South DakotaAugust 4–18
- TennesseeSeptember 7–21
- UtahAugust 29 – September 12
- VermontAugust 13–27
- VirginiaSeptember 9–23
- WashingtonAugust 12–26
- West VirginiaAugust 30 – September 13
- WisconsinAugust 10–24
- WyomingAugust 5–19
Want the frost date itself?
Every window on this page is worked back from a first fall freeze covering a wide area — an average across the zone, or the coldest station in the state. For the station nearest you — plus the last spring freeze and the sprinkler-winterizing deadline the same date sets — use the free first frost date lookup.
Then follow the grass, not the date
Getting the week right is half of it. The other half is the seeding rate, the mow-low and aerate prep, the keep-it-moist watering while it germinates, and the crabgrass pre-emergent you must not put down anywhere near it. Those are grass-specific — start with the step-by-step overseeding guides.