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When to Plant Black Beans in Pierce County, WA

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

Pierce County, Washington is in USDA Zone 8a. The average last spring frost is April 13 and the first fall frost is October 30, giving you a growing season of approximately 200 days.

At an elevation of 168 feet, Pierce County receives approximately 48.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Black Beans to ensure they mature before fall.

Pierce County, WA (Zone 8a) Long season
200 days
Last Spring Frost April 13
200 growing days
First Fall Frost October 30

Pierce County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Transplant: Apr 4 🍅 Harvest: Jul 4 – Aug 22
Recommended (50%) ✓ Fits season (60 days to spare)
Transplant: Apr 13 🍅 Harvest: Jul 13 – Aug 31
Safe Start (90%) ✓ Fits season (52 days to spare)
Transplant: May 16 🍅 Harvest: Aug 15 – Oct 3

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
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Black Beans needs ~1,286 GDD — county provides 2,450 GDD Excellent fit

Black Beans Planting Timeline โ€” Pierce County, WA

Black Beans Planting Calendar

Activity When Date Range
Direct Sow April 20 Apr 20 โ€“ May 11
Harvest July 20 Jul 20 โ€“ Sep 7

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 โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 8a

Growing Season

200 days

Growing Tips for Pierce County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Black Beans in Pierce County, WA?

Pierce County is in Zone 8a with an average last frost of April 13. Plan your Black Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Pierce County, WA?

Pierce County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 13 and first fall frost is October 30.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Pierce County gardeners in Zone 8a 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 Pierce County, WA. Local conditions may vary. Last updated: April 2026.