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When to Plant Black Beans in Lemhi County, ID

Black beans are a warm-season legume producing small, dark, protein-rich beans that are a staple in Latin American and Caribbean cuisines.

Lemhi County, Idaho is in USDA Zone 4b. The average last spring frost is June 9 and the first fall frost is September 14, giving you a growing season of approximately 97 days.

At an elevation of 6,743 feet, Lemhi County receives approximately 12.6 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Black Beans to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Black Beans successfully. Mulch heavily to conserve soil moisture.

Lemhi County, ID (Zone 4b) Very short season
97 days
Last Spring Frost June 9
97 growing days
First Fall Frost September 14

Lemhi County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 14 🍅 Harvest: Aug 13 – Oct 1
Recommended (50%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Sep 8 – Oct 27
Safe Start (90%) ✗ May not fit
Transplant: Jun 25 🍅 Harvest: Sep 24 – Nov 12

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
0.6″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 471 gal / 100 sq ft
Drought risk

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

Black Beans needs ~1,365 GDD — county provides 1,261 GDD Tight fit

Black Beans Planting Timeline โ€” Lemhi County, ID

Black Beans Planting Calendar

Activity When Date Range
Direct Sow June 23 Jun 23 โ€“ Jul 14
Harvest September 22 Sep 22 โ€“ Nov 10

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

90โ€“120 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4b

Growing Season

97 days

Growing Tips for Lemhi County

Direct sow after last frost. Provide support for climbing varieties. Allow pods to dry fully on the vine before harvesting. Thresh dried pods by hand or in a pillowcase.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Level Up Your Garden

Frequently Asked Questions

When should I plant Black Beans in Lemhi County, ID?

Lemhi County is in Zone 4b with an average last frost of June 9. Plan your Black Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Lemhi County, ID?

Lemhi County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 9 and first fall frost is September 14.

๐ŸŒฑ

Plan Your Garden with Confidence

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