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When to Plant Soybeans in Lewis 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.

Lewis County, Idaho is in USDA Zone 6a. The average last spring frost is May 20 and the first fall frost is September 23, giving you a growing season of approximately 126 days.

At an elevation of 4,861 feet, Lewis County receives approximately 13.5 inches of rainfall annually with predominantly loam soil. Summer highs average 90ยฐF, providing good warmth for Soybeans during the growing season. With low rainfall, drip irrigation is essential for growing Soybeans successfully. Mulch heavily to conserve soil moisture.

Lewis County, ID (Zone 6a) Short season
126 days
Last Spring Frost May 20
126 growing days
First Fall Frost September 23

Lewis County Soil Profile

Soil Type

Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Soybeans Planting Timeline โ€” Lewis County, ID

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 27 May 27 โ€“ Jun 17
Harvest August 19 Aug 19 โ€“ Oct 14

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

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

Moderate โ€” regular watering

๐Ÿ“… Days to Maturity

80โ€“120 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: N/A

๐Ÿ—บ๏ธ USDA Zone

Zone 6a

๐Ÿ“† Growing Season

126 days in Lewis County

Growing Tips for Lewis 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Soybeans in Lewis County, ID?

Lewis County is in Zone 6a with an average last frost of May 20. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Lewis County, ID?

Lewis County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 20 and first fall frost is September 23.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Lewis County gardeners in Zone 6a 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 Lewis County, ID. Local conditions may vary. Last updated: April 2026.