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When to Plant Soybeans in Palmer, AK

Palmer, Alaska Zone 4b May

This month in Palmer, Alaska

May is a pivotal month for Palmer, Alaska gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 17
Avg. first frost September 18
Soil temp (4") 51°F
Watering High
Pest pressure Low
Daylight 17.4 hrs
  1. Outdoor sowing time: soybeans

    These tolerate cool soil, so you're not gambling by sowing now.

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Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.

Palmer, Alaska is in USDA Zone 4b. The average last spring frost is May 17 and the first fall frost is September 18, giving you a growing season of approximately 124 days.

At an elevation of 1,177 feet, Palmer receives approximately 52.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 69°F, so choose short-season varieties of Soybeans to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Soybeans root diseases.

Palmer, AK (Zone 4b) Short season
124 days
Last Spring Frost May 17
124 growing days
First Fall Frost September 18

Palmer Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 10 🍅 Harvest: Aug 2 – Sep 27
Recommended (50%) ✗ May not fit
Transplant: May 17 🍅 Harvest: Aug 9 – Oct 4
Safe Start (90%) ✗ May not fit
Transplant: Jun 8 🍅 Harvest: Aug 31 – Oct 26

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 Palmer

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

Soil pH

Your soil pH (4.9–6.7) is more acidic than Soybeans prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Palmer is excellent for Soybeans — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Soybeans.

Organic Matter

Organic matter is excellent (6.8%) — Soybeans will thrive.

How to Plant Soybeans

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Plant Water Budget

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

Monthly Watering Guide for Soybeans

Soybeans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Soybeans Needs Rainfall You Supplement Action
Jan 2.5" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 1.6" 0" ❄️ Dormant
May 4.3" 2.2" 2.1" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 7.4" 0" ✅ Rainfall sufficient
Aug 4.3" 7.7" 0" ✅ Rainfall sufficient
Sep 4.3" 8.3" 0" ✅ Rainfall sufficient
Oct 6.5" 0" ❄️ Dormant
Nov 3.9" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

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

Soybeans 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.

Soybeans needs ~175 GDD — county provides 217 GDD Good fit

Soybeans Planting Timeline — Palmer, AK

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 31 May 31 – Jun 21
Harvest August 23 Aug 23 – Oct 18

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 4b

📆 Growing Season

124 days in Palmer

Growing Tips for Soybeans in Palmer

Direct sow Soybeans outdoors after May 17 in Palmer when soil has warmed and frost danger has passed.

Your 124.0-day growing season in Palmer is tight for Soybeans (80.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Soybeans in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after soil warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Soybeans in Palmer, AK?

Palmer is in Zone 4b with an average last frost of May 17. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Palmer, AK?

Palmer, Alaska is in USDA Hardiness Zone 4b. The average last spring frost is May 17 and first fall frost is September 18.

🌱

Your Palmer Garden Planner — Free

A 24-page printable planner built for Palmer (Zone 4b). 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 Palmer, 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.