Lawn Seeding Weather in New Hampshire: Best Months by City
Lawn Seeding season in New Hampshire, city by city: peak months, season boundaries, and annual workable-day counts from NOAA 1991–2020 normals. Portsmouth leads with 201 workable days a year; Concord runs the shortest at 187.
Across New Hampshire's 4 listed cities, annual workable days for lawn seeding run from 187 (Concord) up to 201 (Portsmouth). Every number comes from NOAA 1991–2020 normals scored against the same label ruleset; every city name links to its live 10-day check.
Statewide, May is the strongest month — it tops or ties the table in most listed cities. The live strips on each city page decide the week; this table decides the month. Scoring rules: methodology; the national playbook: the lawn seeding guide.
Cities in New Hampshire
| City | Peak months | Season | Workable days/yr |
|---|---|---|---|
| Nashua | May, Jul, Aug | April–October | 193 |
| Manchester | May, Jul, Aug | April–October | 197 |
| Portsmouth | May, Jul, Aug | April–October | 201 |
| Concord | May, Jul, Aug | April–October | 187 |
The rules behind these numbers
| Check | Threshold | Why it matters |
|---|---|---|
| Air temperature | 50–85°F (low-temp formulas from 55°F) | Cool-season grasses germinate best with daytime highs of roughly 60–80°F. |
| Overnight low | ≥32°F during the first 48 h (≥40°F preferred) | Seed survives a light frost, but sustained cold stalls germination. |
| Dry before | no soaking (≥1.0") in the prior 24 h | Seeding into mud makes ruts and washes seed into low spots. |
| Dry after | <0.5" rain for 24 h after | Light rain after seeding helps. A 0.5"+ downpour washes seed out. |
| Wind | ≤15 mph (broadcast seed drifts up to 25 mph) | Broadcast spreading above 15 mph lands seed everywhere but the lawn. |
Always follow your product label — formulas vary. The table above is the typical range across major manufacturers, not a promise about your can.
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- Concrete Pouring in New Hampshire
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