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When to Plant Black Beans in Douglas County, WA

Douglas County, Washington Zone 7a May

What to do in May

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

Avg. last frost May 8
Avg. first frost October 4
Soil temp (4") 54°F
Watering Critical
Pest pressure Low
Daylight 14.9 hrs
  1. Outdoor sowing time: black beans

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

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

Douglas County, Washington is in USDA Zone 7a. The average last spring frost is May 8 and the first fall frost is October 4, giving you a growing season of approximately 149 days.

At an elevation of 2,920 feet, Douglas County receives approximately 15.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Black Beans during the growing season. With low rainfall, drip irrigation is essential for growing Black Beans successfully. Mulch heavily to conserve soil moisture.

Douglas County, WA (Zone 7a) Short season
149 days
Last Spring Frost May 8
149 growing days
First Fall Frost October 4
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Douglas County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (20 days to spare)
Transplant: Apr 19 🍅 Harvest: Jul 19 – Sep 6
Recommended (50%) ✓ Fits season (9 days to spare)
Transplant: May 8 🍅 Harvest: Aug 7 – Sep 25
Safe Start (90%) ✓ Fits season (6 days to spare)
Transplant: Jun 10 🍅 Harvest: Sep 9 – Oct 28

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 Douglas County

How your county's soil matches Black Beans's growing requirements.

Soil pH

Your soil pH (5.5–6.2) is more acidic than Black Beans prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.5%) — Black Beans will thrive.

How to Plant Black Beans

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 883 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Black Beans

Black Beans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Black Beans Needs Rainfall You Supplement Action
Jan 2.2" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.2" 0" ❄️ Dormant
May 4.3" 0.8" 3.5" 🚿 Regular watering
Jun 4.3" 0.6" 3.7" 🚿 Regular watering
Jul 4.3" 0.2" 4.1" 🚿 Regular watering
Aug 4.3" 0.3" 4" 🚿 Regular watering
Sep 4.3" 0.7" 3.6" 🚿 Regular watering
Oct 4.3" 1.2" 3.1" 🚿 Regular watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Douglas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Black Beans 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.

Black Beans needs ~1,838 GDD — county provides 2,607 GDD Excellent fit

Black Beans Planting Timeline — Douglas County, WA

Black Beans Planting Calendar

Activity When Date Range
Direct Sow May 15 May 15 – Jun 5
Harvest August 14 Aug 14 – Oct 2

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

149 days in Douglas County

Growing Tips for Black Beans in Douglas County

Direct sow Black Beans outdoors after May 08 in Douglas County when soil has warmed and frost danger has passed.

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

Douglas County receives only 16" of rain annually. Black Beans needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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 Douglas County, WA?

Douglas County is in Zone 7a with an average last frost of May 8. Plan your Black Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Douglas County, WA?

Douglas County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is May 8 and first fall frost is October 4.

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Your Douglas County Garden Planner — Free

A 24-page printable planner built for Douglas County (Zone 7a). 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 Douglas County, WA. 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.