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When to Plant Butternut Squash in Belknap County, NH

Belknap County, New Hampshire Zone 5b May

May in Belknap County, New Hampshire — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Belknap County, New Hampshire.

Avg. last frost May 3
Avg. first frost October 11
Soil temp (4") 57°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Transplant butternut squash outside

    Your last frost (May 3) has passed. These warm-season crops can handle outdoor soil now.

  2. Sow butternut squash where they'll grow

    Your soil is 57°F — warm enough for these to germinate without babying.

Before June arrives, get these ready
  • Starting indoors: butternut squash

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Butternut squash is a popular winter squash with a long neck, small seed cavity, and sweet, nutty orange flesh. It stores exceptionally well for months.

Belknap County, New Hampshire is in USDA Zone 5b. The average last spring frost is May 3 and the first fall frost is October 11, giving you a growing season of approximately 161 days.

At an elevation of 764 feet, Belknap County receives approximately 48.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Butternut Squash during the growing season.

Belknap County, NH (Zone 5b) Moderate season
161 days
Last Spring Frost May 3
161 growing days
First Fall Frost October 11

Belknap County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Mar 24 Transplant: May 12 🍅 Harvest: Aug 11 – Sep 15
Recommended (50%) ✓ Fits season (21 days to spare)
Start indoors: Mar 29 Transplant: May 17 🍅 Harvest: Aug 16 – Sep 20
Safe Start (90%) ✓ Fits season (25 days to spare)
Start indoors: Apr 12 Transplant: May 31 🍅 Harvest: Aug 30 – Oct 4

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.

Soil Compatibility in Belknap County

How your county's soil matches Butternut Squash's growing requirements.

Soil pH

Your soil pH (4.8–6.8) is more acidic than Butternut Squash prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Belknap County is excellent for Butternut Squash — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Butternut Squash.

How to Plant Butternut Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Butternut Squash

Butternut Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Butternut Squash Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 3.4" 0" ❄️ Dormant
Mar 4.4" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.8" 3.9" 0.9" 💧 Light watering
Jun 4.8" 4.7" 0.1" 💧 Light watering
Jul 4.8" 4.9" 0" ✅ Rainfall sufficient
Aug 4.8" 4.8" 0" ✅ Rainfall sufficient
Sep 4.8" 3.8" 1" 💧 Light watering
Oct 4.8" 4.4" 0.4" 💧 Light watering
Nov 3.8" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Belknap County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Butternut Squash Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Butternut Squash needs ~1,487 GDD — county provides 2,455 GDD Excellent fit

Butternut Squash Planting Timeline — Belknap County, NH

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest August 16 Aug 16 – Sep 20

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Natural rainfall sufficient

📅 Days to Maturity

85–110 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5b

📆 Growing Season

161 days in Belknap County

Growing Tips for Butternut Squash in Belknap County

Direct sow Butternut Squash outdoors after May 03 in Belknap County when soil has warmed and frost danger has passed.

Common pests for Butternut Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 3 weeks early or direct sow after frost. Allow 6-8 feet for sprawling vines. Harvest when the skin is hard and uniformly tan. Cure in the sun for 10 days.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Butternut Squash in Belknap County, NH?

Belknap County is in Zone 5b with an average last frost of May 3. Plan your Butternut Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Belknap County, NH?

Belknap County, New Hampshire is in USDA Hardiness Zone 5b. The average last spring frost is May 3 and first fall frost is October 11.

🌱

Your Belknap County Garden Planner — Free

A 24-page printable planner built for Belknap County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Belknap County, NH. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.