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When to Plant Sweet Corn in Franklin County, ME

Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.

Franklin County, Maine is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 28, giving you a growing season of approximately 137 days.

At an elevation of 244 feet, Franklin County receives approximately 40.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Sweet Corn to ensure they mature before fall.

Franklin County, ME (Zone 4a) Short season
137 days
Last Spring Frost May 14
137 growing days
First Fall Frost September 28

Franklin County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Aug 24
Recommended (50%) ✓ Fits season (32 days to spare)
Transplant: May 14 🍅 Harvest: Jul 16 – Aug 27
Safe Start (90%) ✓ Fits season (28 days to spare)
Transplant: May 31 🍅 Harvest: Aug 2 – Sep 13

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
Sweet Corn needs ~750 GDD — county provides 1,370 GDD Excellent fit

Sweet Corn Planting Timeline โ€” Franklin County, ME

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow May 28 May 28 โ€“ Jun 18
Harvest July 30 Jul 30 โ€“ Sep 10

Plant 1" deep ยท 12" apart ยท Rows 36" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Direct Sow
June 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

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

137 days

Growing Tips for Franklin County

Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Sweet Corn in Franklin County, ME?

Franklin County is in Zone 4a with an average last frost of May 14. Plan your Sweet Corn planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Franklin County, ME?

Franklin County, Maine is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Franklin County gardeners in Zone 4a 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 Franklin County, ME. Local conditions may vary. Last updated: April 2026.