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When to Plant Cowpeas in Williamson County, TX

Williamson County, Texas Zone 9a May

What to do in May

Your garden in Williamson County, Texas is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost March 5
Avg. first frost November 22
Soil temp (4") 72°F
Watering Low
Pest pressure High
Daylight 13.6 hrs
  1. Harvest cowpeas as they ripen

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

A few tasks this May that'll pay off in June
  • First harvests: cowpeas

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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.

Williamson County, Texas is in USDA Zone 9a. The average last spring frost is March 5 and the first fall frost is November 22, giving you a growing season of approximately 262 days.

At an elevation of 1,023 feet, Williamson County receives approximately 53.3 inches of rainfall annually with predominantly clay soil. Summer highs average 94°F, providing good warmth for Cowpeas during the growing season. Clay soil retains moisture well for Cowpeas, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cowpeas root diseases.

Williamson County, TX (Zone 9a) Long season
262 days
Last Spring Frost March 5
262 growing days
First Fall Frost November 22
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Williamson County Soil Profile

Soil Type

Clay

Soil pH

7.1-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (159 days to spare)
Transplant: Feb 21 🍅 Harvest: Apr 25 – Jun 6
Recommended (50%) ✓ Fits season (157 days to spare)
Transplant: Mar 5 🍅 Harvest: May 7 – Jun 18
Safe Start (90%) ✓ Fits season (145 days to spare)
Transplant: Apr 6 🍅 Harvest: Jun 8 – Jul 20

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 Williamson County

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

Soil pH

Your soil pH (7.1–7.8) is more alkaline than Cowpeas prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (46% clay) in Williamson County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Drainage

Cowpeas prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Cowpeas.

How to Plant Cowpeas

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

Succession Planting Cowpeas

5
successive plantings in your 262-day season

Sow every 6.9 weeks. Last sowing by Aug 24 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 1.4" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.2" 3.4" 0" ✅ Rainfall sufficient
Apr 2.2" 6.5" 0" ✅ Rainfall sufficient
May 2.2" 7.7" 0" ✅ Rainfall sufficient
Jun 2.2" 7.6" 0" ✅ Rainfall sufficient
Jul 2.2" 6.6" 0" ✅ Rainfall sufficient
Aug 2.2" 6.1" 0" ✅ Rainfall sufficient
Sep 2.2" 5.4" 0" ✅ Rainfall sufficient
Oct 2.2" 3.7" 0" ✅ Rainfall sufficient
Nov 2.2" 1.7" 0.5" 💧 Light watering
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Williamson County). Supplement amounts are based on average rainfall — 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" — every day above 50°F 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 ~1,538 GDD — county provides 5,371 GDD Excellent fit

Cowpeas Planting Timeline — Williamson County, TX

Cowpeas Planting Calendar

Activity When Date Range
Direct Sow March 12 Mar 12 – Apr 2
Harvest May 14 May 14 – Jun 25

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9a

📆 Growing Season

262 days in Williamson County

Growing Tips for Cowpeas in Williamson County

Direct sow Cowpeas outdoors after March 05 in Williamson County when soil has warmed and frost danger has passed.

With Williamson County's clay soil (46% clay), work in 3-4 inches of compost before planting Cowpeas. Avoid tilling when soil is wet to prevent compaction.

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 Williamson County, TX?

Williamson County is in Zone 9a with an average last frost of March 5. Plan your Cowpeas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Williamson County, TX?

Williamson County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 5 and first fall frost is November 22.

🌱

Your Williamson County Garden Planner — Free

A 24-page printable planner built for Williamson County (Zone 9a). 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 Williamson County, TX. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.