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When to Plant Soybeans in Blue Earth County, MN

Blue Earth County, Minnesota Zone 5a May

May in the garden — Blue Earth County, Minnesota

We've pulled the most time-sensitive tasks for Blue Earth County, Minnesota this May and put them front and centre. Tackle them in order.

Avg. last frost April 29
Avg. first frost October 4
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Put soybeans seeds straight in the ground

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

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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.

Blue Earth County, Minnesota is in USDA Zone 5a. The average last spring frost is April 29 and the first fall frost is October 4, giving you a growing season of approximately 158 days.

At an elevation of 646 feet, Blue Earth County receives approximately 40.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Soybeans to ensure they mature before fall.

Blue Earth County, MN (Zone 5a) Moderate season
158 days
Last Spring Frost April 29
158 growing days
First Fall Frost October 4
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Blue Earth County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Transplant: Apr 24 🍅 Harvest: Jul 17 – Sep 11
Recommended (50%) ✓ Fits season (18 days to spare)
Transplant: Apr 29 🍅 Harvest: Jul 22 – Sep 16
Safe Start (90%) ✓ Fits season (15 days to spare)
Transplant: May 14 🍅 Harvest: Aug 6 – Oct 1

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 Blue Earth County

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

Soil pH

Your soil pH (5.9–6.8) overlaps with Soybeans's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Soybeans.

How to Plant Soybeans

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

Succession Planting Soybeans

2
successive plantings in your 158-day season

Sow every 9.1 weeks. Last sowing by Jun 06 to harvest before frost.

Plant Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.6" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 4.3" 0" ✅ Rainfall sufficient
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 5.1" 0" ✅ Rainfall sufficient
Aug 4.3" 4.4" 0" ✅ Rainfall sufficient
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Blue Earth County). 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 ~1,150 GDD — county provides 1,817 GDD Excellent fit

Soybeans Planting Timeline — Blue Earth County, MN

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 6 May 6 – May 27
Harvest July 29 Jul 29 – Sep 23

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 5a

📆 Growing Season

158 days in Blue Earth County

Growing Tips for Soybeans in Blue Earth County

Direct sow Soybeans outdoors after April 29 in Blue Earth County when soil has warmed and frost danger has passed.

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 Blue Earth County, MN?

Blue Earth County is in Zone 5a with an average last frost of April 29. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Blue Earth County, MN?

Blue Earth County, Minnesota is in USDA Hardiness Zone 5a. The average last spring frost is April 29 and first fall frost is October 4.

🌱

Your Blue Earth County Garden Planner — Free

A 24-page printable planner built for Blue Earth County (Zone 5a). 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 Blue Earth County, MN. 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.