When to Plant Grass Seed in New Hampshire

Cool-season lawns dominate New Hampshire, and for cool-season seed fall is the better window, with spring the second choice. The dates below are typical crossings from in-state monitoring stations; your city page tracks the live reading.

Best Time to Plant Grass Seed in New Hampshire

Cool-season · fall window

July 27

July 19 (coolest parts) to July 27 (warmest)

For cool-season lawns (fescue, bluegrass, ryegrass), fall is the best time to plant grass seed in New Hampshire, with spring the second choice: fall seedlings face less weed competition and mature before summer heat. The window opens as 2-inch soil falls back through 70°F, and germination slows sharply once soil drops below 50°F, typically around October 28. Fall seeding and fall pre-emergent are an either/or on the same turf; see pre-emergent timing in New Hampshire.

Cool-season · spring window

April 29

April 15 (warmest parts) to May 14 (coolest)

Spring is the second choice: the window opens when soil first holds 50°F and narrows as soil passes 65°F, typically by June 20.

Fall seeding also needs a stop date: new seedlings want about six weeks of growth before frost arrives. Your city page estimates the last safe seeding date from its nearest station: see when to plant in Manchester, when to plant in Nashua or when to plant in Concord. Today's statewide reading is on the New Hampshire soil temperature page.

Typical dates are computed from historical 2-inch soil temperature averages at 3 monitoring stations in New Hampshire; your own window depends on your nearest station's readings.

Best Time to Plant Grass Seed in New Hampshire: Month by Month

Typical 2-inch soil temperature by month across New Hampshire, the median of 3 in-state stations with multi-year records, with the seeding verdict for each grass family. Confirm against the current reading on your city page before you put seed down.

Month	Typical 2" soil temp	Cool-season seeding	Warm-season seeding
January	33°F	Dormant	Too cold
February	33°F	Dormant	Too cold
March	35°F	Dormant	Too cold
April	45°F	Too cold	Too cold
May	56°F	Good; fall is better	Too cold
June	64°F	Good; fall is better	Approaching
July	69°F	Risky; heat ahead	Prime window
August	69°F	Soon; still cooling	Too late this year
September	63°F	Prime window	Too cold
October	54°F	Prime window	Too cold
November	43°F	Too cold	Too cold
December	36°F	Dormant	Too cold