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When to Plant Soybeans in Isanti County, MN

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.

Isanti County, Minnesota is in USDA Zone 4a. The average last spring frost is May 3 and the first fall frost is October 1, giving you a growing season of approximately 151 days.

At an elevation of 514 feet, Isanti County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Soybeans to ensure they mature before fall.

Isanti County, MN (Zone 4a) Moderate season
151 days
Last Spring Frost May 3
151 growing days
First Fall Frost October 1

Isanti County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Transplant: Apr 28 🍅 Harvest: Jul 21 – Sep 15
Recommended (50%) ✓ Fits season (11 days to spare)
Transplant: May 3 🍅 Harvest: Jul 26 – Sep 20
Safe Start (90%) ✓ Fits season (9 days to spare)
Transplant: May 19 🍅 Harvest: Aug 11 – Oct 6

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
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 487 gal / 100 sq ft
Soybeans needs ~1,075 GDD — county provides 1,623 GDD Excellent fit

Soybeans Planting Timeline โ€” Isanti County, MN

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 17 May 17 โ€“ Jun 7
Harvest August 9 Aug 9 โ€“ Oct 4

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

151 days

Growing Tips for Isanti County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Soybeans in Isanti County, MN?

Isanti County is in Zone 4a with an average last frost of May 3. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Isanti County, MN?

Isanti County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 3 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Isanti 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 Isanti County, MN. Local conditions may vary. Last updated: April 2026.