Blog

When to Plant Garlic in Grand Isle County, VT

Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

Grand Isle County, Vermont is in USDA Zone 4b. 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 84ยฐF, so choose short-season varieties of Garlic to ensure they mature before fall.

Grand Isle County, VT (Zone 4b) Moderate season
157 days
Last Spring Frost May 6
157 growing days
First Fall Frost October 10

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 (11 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 30 – Sep 24
Recommended (50%) ✓ Fits season (10 days to spare)
Transplant: May 6 🍅 Harvest: Aug 5 – Sep 30
Safe Start (90%) ✓ Fits season (12 days to spare)
Transplant: May 17 🍅 Harvest: Aug 16 – Oct 11

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Garlic needs ~2,145 GDD — county provides 2,041 GDD Tight fit

Garlic Planting Timeline โ€” Grand Isle County, VT

Garlic Planting Calendar

Activity When Date Range
Fall Sowing August 29 Aug 29 โ€“ Sep 12

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June โ€”
July โ€”
August Fall Sowing
September Fall Sowing
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“240 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4b

Growing Season

157 days

Growing Tips for Grand Isle County

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Level Up Your Garden

Frequently Asked Questions

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

Grand Isle County is in Zone 4b with an average last frost of May 6. Plan your Garlic planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Grand Isle County, VT?

Grand Isle County, Vermont is in USDA Hardiness Zone 4b. The average last spring frost is May 6 and first fall frost is October 10.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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: April 2026.