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When to Plant Cowpeas in Grundy County, IL

Cowpeas (black-eyed peas) are a heat-loving legume that fixes nitrogen in the soil. They are drought-tolerant and produce protein-rich pods in hot conditions.

Grundy County, Illinois is in USDA Zone 5a. The average last spring frost is April 20 and the first fall frost is October 17, giving you a growing season of approximately 180 days.

At an elevation of 629 feet, Grundy County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Cowpeas during the growing season.

Grundy County, IL (Zone 5a) Moderate season
180 days
Last Spring Frost April 20
180 growing days
First Fall Frost October 17

Grundy County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (77 days to spare)
Transplant: Apr 14 🍅 Harvest: Jun 16 – Jul 28
Recommended (50%) ✓ Fits season (75 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 3
Safe Start (90%) ✓ Fits season (70 days to spare)
Transplant: May 9 🍅 Harvest: Jul 11 – Aug 22

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
0.5″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Cowpeas needs ~1,031 GDD — county provides 2,475 GDD Excellent fit

Cowpeas Planting Timeline โ€” Grundy County, IL

Cowpeas Planting Calendar

Activity When Date Range
Direct Sow April 27 Apr 27 โ€“ May 18
Harvest June 29 Jun 29 โ€“ Aug 10

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

60โ€“90 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 5a

Growing Season

180 days

Growing Tips for Grundy County

Direct sow after soil is thoroughly warm. Do not over-fertilize with nitrogen as cowpeas fix their own. Harvest pods when they begin to dry on the vine for dry beans.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Onion

Level Up Your Garden

Frequently Asked Questions

When should I plant Cowpeas in Grundy County, IL?

Grundy County is in Zone 5a with an average last frost of April 20. Plan your Cowpeas planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Grundy County, IL?

Grundy County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 20 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Grundy County gardeners in Zone 5a 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 Grundy County, IL. Local conditions may vary. Last updated: April 2026.