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When to Plant Cowpeas in Mason 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.

Mason County, Illinois is in USDA Zone 5b. The average last spring frost is April 15 and the first fall frost is October 14, giving you a growing season of approximately 182 days.

At an elevation of 768 feet, Mason County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Cowpeas during the growing season.

Mason County, IL (Zone 5b) Moderate season
182 days
Last Spring Frost April 15
182 growing days
First Fall Frost October 14

Mason County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (73 days to spare)
Transplant: Apr 12 🍅 Harvest: Jun 14 – Jul 26
Recommended (50%) ✓ Fits season (77 days to spare)
Transplant: Apr 15 🍅 Harvest: Jun 17 – Jul 29
Safe Start (90%) ✓ Fits season (76 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 2 – Aug 13

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.

Soil Compatibility in Mason County

How your county's soil matches Cowpeas's growing requirements.

Soil pH

Your soil pH (6.1โ€“6.9) is within Cowpeas's preferred range (5.5โ€“7.0).

Soil Texture

The silt loam soil in Mason County is excellent for Cowpeas โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.8%) โ€” Cowpeas will thrive.

How to Plant Cowpeas

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Cowpeas

3
successive plantings in your 182-day season

Sow every 6.9 weeks. Last sowing by Jul 16 to harvest before frost.

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

Monthly Watering Guide for Cowpeas

Cowpeas needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Cowpeas Needs Rainfall You Supplement Action
Jan โ€” 1.3" 0" โ„๏ธ Dormant
Feb โ€” 1.5" 0" โ„๏ธ Dormant
Mar โ€” 2" 0" โ„๏ธ Dormant
Apr 2.2" 3" 0" โœ… Rainfall sufficient
May 2.2" 3.3" 0" โœ… Rainfall sufficient
Jun 2.2" 4.1" 0" โœ… Rainfall sufficient
Jul 2.2" 3.3" 0" โœ… Rainfall sufficient
Aug 2.2" 3.4" 0" โœ… Rainfall sufficient
Sep 2.2" 2.7" 0" โœ… Rainfall sufficient
Oct 2.2" 2.2" 0" โœ… Rainfall sufficient
Nov โ€” 2" 0" โ„๏ธ Dormant
Dec โ€” 1.8" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Mason County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Cowpeas Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" โ€” every day above 50ยฐF deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Cowpeas needs ~1,088 GDD — county provides 2,639 GDD Excellent fit

Cowpeas Planting Timeline โ€” Mason County, IL

Cowpeas Planting Calendar

Activity When Date Range
Direct Sow April 22 Apr 22 โ€“ May 13
Harvest June 24 Jun 24 โ€“ Aug 5

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

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.5"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

60โ€“90 days

๐Ÿงช Soil pH

Needs 5.5โ€“7 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 5b

๐Ÿ“† Growing Season

182 days in Mason County

Growing Tips for Cowpeas in Mason County

Direct sow Cowpeas outdoors after April 15 in Mason County when soil has warmed and frost danger has passed.

Common pests for Cowpeas in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cowpeas in Mason County, IL?

Mason County is in Zone 5b with an average last frost of April 15. Plan your Cowpeas planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Mason County, IL?

Mason County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 15 and first fall frost is October 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Mason County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Mason County, IL. Local conditions may vary. Last updated: April 2026.