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When to Plant Tomatoes in Fairbanks North Star Borough, AK

Fairbanks North Star Borough, Alaska Zone 3b May

Your May game plan for Fairbanks North Star Borough, Alaska

A quick May briefing for Fairbanks North Star Borough, Alaska gardeners — what's urgent, what's next, and what can wait.

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. Put tomatoes seeds straight in the ground

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

A few tasks this May that'll pay off in June
  • Transplants going out: tomatoes

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Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

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 Tomatoes 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

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) ✗ May not fit
Start indoors: Mar 9 Transplant: Jun 1 🍅 Harvest: Aug 3 – Oct 5
Recommended (50%) ✗ May not fit
Start indoors: Mar 13 Transplant: Jun 5 🍅 Harvest: Aug 7 – Oct 9
Safe Start (90%) ✗ May not fit
Start indoors: Mar 28 Transplant: Jun 20 🍅 Harvest: Aug 22 – Oct 24

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 Tomatoes's growing requirements.

Soil pH

Your soil pH (5.2–6.4) is more acidic than Tomatoes 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 Tomatoes — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Tomatoes.

Organic Matter

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

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

Succession Planting Tomatoes

2
successive plantings in your 116-day season

Sow every 6.9 weeks. Last sowing by Jun 15 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Tomatoes

Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Tomatoes Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1" 0" ❄️ Dormant
May 5.2" 1.2" 4" 🚿 Regular watering
Jun 5.2" 2.4" 2.8" 🚿 Regular watering
Jul 5.2" 3.3" 1.9" 💧 Light watering
Aug 5.2" 4.1" 1.1" 💧 Light watering
Sep 5.2" 5.3" 0" ✅ Rainfall sufficient
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.

Tomatoes 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.

Tomatoes needs ~127 GDD — county provides 203 GDD Excellent fit

Tomatoes Planting Timeline — Fairbanks North Star Borough, AK

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors June 5 Jun 5 – Jun 19
Direct Sow May 29 May 29 – Jun 19
Harvest August 7 Aug 7 – Oct 9

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Natural rainfall sufficient

📅 Days to Maturity

60–85 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 Tomatoes in Fairbanks North Star Borough

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

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Fairbanks North Star Borough

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

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

Fairbanks North Star Borough is in Zone 3b with an average last frost of May 15. Plan your Tomatoes 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.

🌱

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.