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When to plant Black Beans in Union County, IA

Black Beans planted in Union County between April 30 and May 21 matures in 90–120 days — well before the October 11 first frost.

When to Plant Black Beans in Union County, IA

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

Union County, Iowa is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 11, giving you a growing season of approximately 171 days.

At an elevation of 1,311 feet, Union County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Black Beans to ensure they mature before fall.

Union County, IA (Zone 5b) Moderate season
171 days
Last Spring Frost April 23
171 growing days
First Fall Frost October 11

Union County Soil Profile

Soil Type

Silt Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Black Beans Planting Timeline — Union County, IA

Black Beans Planting Calendar

Activity When Date Range
Direct Sow April 30 Apr 30 – May 21
Harvest July 30 Jul 30 – Sep 17

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: N/A

🗺️ USDA Zone

Zone 5b

📆 Growing Season

171 days in Union County

Growing Tips for Union 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Black Beans in Union County, IA?

Union County is in Zone 5b with an average last frost of April 23. Plan your Black Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, IA?

Union County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 11.

When should I plant Black Beans in Union County, IA?

In Union County, IA, plant Black Beans after the last frost (around April 23) and before the first frost (around October 11). Best results when soil holds above 50°F.

What growing zone is Union County, IA for Black Beans?

Union County sits in USDA Zone 5b. Black Beans grows reliably in zones 3a through 11b, so it's a good fit here.

Can Black Beans grow in Union County's climate?

Yes — Black Beans grows well in Union County's temperate climate. Union County averages a 171-day frost-free season, with last frost around April 23 and first frost around October 11.

🌱

Your Union County Garden Planner — Free

A 22-page printable planner built for Union County (Zone 5b). 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 Union County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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