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When to Plant Soybeans in Butte County, ID

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.

Butte County, Idaho is in USDA Zone 4b. The average last spring frost is June 1 and the first fall frost is September 14, giving you a growing season of approximately 105 days.

At an elevation of 7,254 feet, Butte County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Soybeans to ensure they mature before fall.

Butte County, ID (Zone 4b) Short season
105 days
Last Spring Frost June 1
105 growing days
First Fall Frost September 14

Butte County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 21 🍅 Harvest: Aug 13 – Oct 8
Recommended (50%) ✗ May not fit
Transplant: Jun 1 🍅 Harvest: Aug 24 – Oct 19
Safe Start (90%) ✗ May not fit
Transplant: Jun 17 🍅 Harvest: Sep 9 – Nov 4

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
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 45 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Soybeans needs ~1,300 GDD — county provides 1,365 GDD Good fit

Soybeans Planting Timeline โ€” Butte County, ID

Soybeans Planting Calendar

Activity When Date Range
Direct Sow June 15 Jun 15 โ€“ Jul 6
Harvest September 7 Sep 7 โ€“ Nov 2

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June Direct Sow
July Direct Sow
August โ€”
September Harvest
October Harvest
November Harvest
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 4b

Growing Season

105 days

Growing Tips for Butte 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 Butte County, ID?

Butte County is in Zone 4b with an average last frost of June 1. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Butte County, ID?

Butte County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 1 and first fall frost is September 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Butte County gardeners in Zone 4b 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 Butte County, ID. Local conditions may vary. Last updated: April 2026.