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When to Plant Sweet Corn in Fairbanks North Star Borough, AK

Fairbanks North Star Borough, Alaska Zone 3b May

Your May gardening checklist

Your Fairbanks North Star Borough, Alaska garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 15
Avg. first frost September 8
Soil temp (4") 42°F
Watering Critical
Pest pressure Low
Daylight 18.2 hrs
  1. Plant sweet corn from seed, right in the garden

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

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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.

Fairbanks North Star Borough, Alaska is in USDA Zone 3b. The average last spring frost is May 15 and the first fall frost is September 8, giving you a growing season of approximately 116 days.

At an elevation of 2,540 feet, Fairbanks North Star Borough receives approximately 29.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 69°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.

Fairbanks North Star Borough, AK (Zone 3b) Short season
116 days
Last Spring Frost May 15
116 growing days
First Fall Frost September 8
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Fairbanks North Star Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (9 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Aug 24
Recommended (50%) ✓ Fits season (11 days to spare)
Transplant: May 15 🍅 Harvest: Jul 17 – Aug 28
Safe Start (90%) ✓ Fits season (9 days to spare)
Transplant: May 30 🍅 Harvest: Aug 1 – Sep 12

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 Fairbanks North Star Borough

How your county's soil matches Sweet Corn's growing requirements.

Soil pH

Your soil pH (5.2–6.4) is more acidic than Sweet Corn prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Fairbanks North Star Borough is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Sweet Corn.

Organic Matter

Organic matter is excellent (6.7%) — Sweet Corn will thrive.

How to Plant Sweet Corn

1"
Planting Depth
12"
Between Plants
36"
Between Rows

Succession Planting Sweet Corn

2
successive plantings in your 116-day season

Sow every 6.9 weeks. Last sowing by Jun 10 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Sweet Corn

Sweet Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Sweet Corn Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1" 0" ❄️ Dormant
May 6.5" 1.2" 5.3" 🚿 Regular watering
Jun 6.5" 2.4" 4.1" 🚿 Regular watering
Jul 6.5" 3.3" 3.2" 💧 Light watering
Aug 6.5" 4.1" 2.4" 💧 Light watering
Sep 6.5" 5.3" 1.2" 💧 Light watering
Oct 3.8" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Fairbanks North Star Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Sweet Corn 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.

Sweet Corn needs ~131 GDD — county provides 203 GDD Excellent fit

Sweet Corn Planting Timeline — Fairbanks North Star Borough, AK

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow May 29 May 29 – Jun 19
Harvest July 31 Jul 31 – Sep 11

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 3b

📆 Growing Season

116 days in Fairbanks North Star Borough

Growing Tips for Sweet Corn in Fairbanks North Star Borough

Direct sow Sweet Corn outdoors after May 15 in Fairbanks North Star Borough when soil has warmed and frost danger has passed.

Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sweet Corn in Fairbanks North Star Borough, AK?

Fairbanks North Star Borough is in Zone 3b with an average last frost of May 15. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fairbanks North Star Borough, AK?

Fairbanks North Star Borough, Alaska is in USDA Hardiness Zone 3b. The average last spring frost is May 15 and first fall frost is September 8.

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Your Fairbanks North Star Borough Garden Planner — Free

A 24-page printable planner built for Fairbanks North Star Borough (Zone 3b). 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 Fairbanks North Star Borough, AK. 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.