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When to Plant Pumpkin in Grand Isle County, VT

Grand Isle County, Vermont Zone 5a May

Grand Isle County, Vermont gardeners: here's your May plan

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

Avg. last frost May 6
Avg. first frost October 10
Soil temp (4") 55°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Time to transplant pumpkin

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Seed pumpkin outdoors

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

June will be here before you know it — start on
  • Starting indoors: pumpkin

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Pumpkins are large-fruited squash varieties grown for eating, decoration, and seed production. They require ample space and a long, warm growing season.

Grand Isle County, Vermont is in USDA Zone 5a. The average last spring frost is May 6 and the first fall frost is October 10, giving you a growing season of approximately 157 days.

At an elevation of 1,011 feet, Grand Isle County receives approximately 38.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Pumpkin to ensure they mature before fall.

Grand Isle County, VT (Zone 5a) Moderate season
157 days
Last Spring Frost May 6
157 growing days
First Fall Frost October 10
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Grand Isle County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 26 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 1
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Apr 1 Transplant: May 20 🍅 Harvest: Aug 19 – Oct 7
Safe Start (90%) ✓ Fits season (5 days to spare)
Start indoors: Apr 12 Transplant: May 31 🍅 Harvest: Aug 30 – Oct 18

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 Grand Isle County

How your county's soil matches Pumpkin's growing requirements.

Soil pH

Your soil pH (4.8–6.4) is more acidic than Pumpkin prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Grand Isle County is excellent for Pumpkin — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Pumpkin.

How to Plant Pumpkin

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

Plant Water Budget

Plant needs
1.3″/week
Rainfall provides
1.0″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 374 gal / 100 sq ft

Monthly Watering Guide for Pumpkin

Pumpkin needs approximately 1.3 inches of water per week (5.6" per month). Here's how your county's rainfall compares month by month.

Month Pumpkin Needs Rainfall You Supplement Action
Jan 2.5" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 3.2" 0" ❄️ Dormant
Apr 3.1" 0" ❄️ Dormant
May 5.6" 3.6" 2" 💧 Light watering
Jun 5.6" 3.5" 2.1" 💧 Light watering
Jul 5.6" 4.3" 1.3" 💧 Light watering
Aug 5.6" 3.5" 2.1" 💧 Light watering
Sep 5.6" 3.6" 2" 💧 Light watering
Oct 5.6" 2.8" 2.8" 🚿 Regular watering
Nov 3.2" 0" ❄️ Dormant
Dec 2.7" 0" ❄️ Dormant

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

Pumpkin 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.

Pumpkin needs ~1,332 GDD — county provides 2,041 GDD Excellent fit

Pumpkin Planting Timeline — Grand Isle County, VT

Pumpkin Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 13 May 13 – Jun 3
Harvest August 19 Aug 19 – Oct 7

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · Only during dry spells

📅 Days to Maturity

85–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

157 days in Grand Isle County

Growing Tips for Pumpkin in Grand Isle County

Direct sow Pumpkin outdoors after May 06 in Grand Isle County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow on mounds after last frost. Allow 6-10 feet between plants. Slip a board under developing fruit to prevent rot. Harvest when rind is hard and deep in color.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pumpkin in Grand Isle County, VT?

Grand Isle County is in Zone 5a with an average last frost of May 6. Plan your Pumpkin planting based on this frost date — see the calendar above for exact timing.

What planting zone is Grand Isle County, VT?

Grand Isle County, Vermont is in USDA Hardiness Zone 5a. The average last spring frost is May 6 and first fall frost is October 10.

🌱

Your Grand Isle County Garden Planner — Free

A 24-page printable planner built for Grand Isle County (Zone 5a). 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 Grand Isle County, VT. 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.