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When to Plant Squash (Summer) in Grafton County, NH

Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

Grafton County, New Hampshire is in USDA Zone 4b. The average last spring frost is May 12 and the first fall frost is October 7, giving you a growing season of approximately 148 days.

At an elevation of 524 feet, Grafton County receives approximately 44.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Squash (Summer) to ensure they mature before fall.

Grafton County, NH (Zone 4b) Short season
148 days
Last Spring Frost May 12
148 growing days
First Fall Frost October 7

Grafton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (17 days to spare)
Start indoors: Mar 25 Transplant: May 27 🍅 Harvest: Jul 15 – Sep 16
Recommended (50%) ✓ Fits season (15 days to spare)
Start indoors: Mar 31 Transplant: Jun 2 🍅 Harvest: Jul 21 – Sep 22
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 13 Transplant: Jun 15 🍅 Harvest: Aug 3 – Oct 5

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Squash (Summer) needs ~550 GDD — county provides 1,480 GDD Excellent fit

Squash (Summer) Planting Timeline โ€” Grafton County, NH

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 โ€“ Apr 14
Transplant Outdoors June 2 Jun 2 โ€“ Jun 16
Direct Sow May 26 May 26 โ€“ Jun 16
Harvest July 21 Jul 21 โ€“ Sep 22

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

45โ€“65 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4b

Growing Season

148 days

Growing Tips for Grafton County

Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Squash (Summer) in Grafton County, NH?

Grafton County is in Zone 4b with an average last frost of May 12. Plan your Squash (Summer) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Grafton County, NH?

Grafton County, New Hampshire is in USDA Hardiness Zone 4b. The average last spring frost is May 12 and first fall frost is October 7.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Grafton County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Grafton County, NH. Local conditions may vary. Last updated: April 2026.