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When to Plant Cowpeas in Clackamas County, OR

Clackamas County, Oregon Zone 9a May

Your May game plan for Clackamas County, Oregon

Each item below is timed to Clackamas County, Oregon's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 14
Avg. first frost October 28
Soil temp (4") 73°F
Watering Moderate
Pest pressure High
Daylight 14.7 hrs
To set up a strong June, finish these tasks
  • 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.

Clackamas County, Oregon is in USDA Zone 9a. The average last spring frost is April 14 and the first fall frost is October 28, giving you a growing season of approximately 197 days.

At an elevation of 199 feet, Clackamas County receives approximately 53.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Cowpeas during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cowpeas root diseases.

Clackamas County, OR (Zone 9a) Moderate season
197 days
Last Spring Frost April 14
197 growing days
First Fall Frost October 28

Clackamas County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (92 days to spare)
Transplant: Apr 4 🍅 Harvest: Jun 6 – Jul 18
Recommended (50%) ✓ Fits season (92 days to spare)
Transplant: Apr 14 🍅 Harvest: Jun 16 – Jul 28
Safe Start (90%) ✓ Fits season (96 days to spare)
Transplant: May 7 🍅 Harvest: Jul 9 – Aug 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 Clackamas County

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

Soil pH

Your soil pH (5.7–6.3) is within Cowpeas's preferred range (5.5–7.0).

Soil Texture

The silt loam soil in Clackamas County is excellent for Cowpeas — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.7%) — Cowpeas will thrive.

How to Plant Cowpeas

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

Succession Planting Cowpeas

3
successive plantings in your 197-day season

Sow every 6.9 weeks. Last sowing by Jul 30 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/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 8.3" 0" ❄️ Dormant
Feb 5.3" 0" ❄️ Dormant
Mar 4.8" 0" ❄️ Dormant
Apr 2.2" 4" 0" ✅ Rainfall sufficient
May 2.2" 3.3" 0" ✅ Rainfall sufficient
Jun 2.2" 2.1" 0.1" 💧 Light watering
Jul 2.2" 0.8" 1.4" 🚿 Regular watering
Aug 2.2" 1" 1.2" 🚿 Regular watering
Sep 2.2" 2.2" 0" ✅ Rainfall sufficient
Oct 2.2" 4.7" 0" ✅ Rainfall sufficient
Nov 8.2" 0" ❄️ Dormant
Dec 8.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Clackamas 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 ~1,031 GDD — county provides 2,708 GDD Excellent fit

Cowpeas Planting Timeline — Clackamas County, OR

Cowpeas Planting Calendar

Activity When Date Range
Direct Sow April 21 Apr 21 – May 12
Harvest June 23 Jun 23 – Aug 4

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

Month-by-Month Timeline

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

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: ideal

🗺️ USDA Zone

Zone 9a

📆 Growing Season

197 days in Clackamas County

Growing Tips for Cowpeas in Clackamas County

Direct sow Cowpeas outdoors after April 14 in Clackamas 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 Clackamas County, OR?

Clackamas County is in Zone 9a with an average last frost of April 14. Plan your Cowpeas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clackamas County, OR?

Clackamas County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 14 and first fall frost is October 28.

🌱

Your Clackamas County Garden Planner — Free

A 24-page printable planner built for Clackamas 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 Clackamas County, OR. 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.