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When to Plant Black Beans in Petersburg Borough, AK

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

Petersburg Borough, Alaska is in USDA Zone 7a. The average last spring frost is April 23 and the first fall frost is October 20, giving you a growing season of approximately 180 days.

At an elevation of 974 feet, Petersburg Borough receives approximately 17.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 57ยฐF, so choose short-season varieties of Black Beans to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Black Beans successfully. Mulch heavily to conserve soil moisture.

Petersburg Borough, AK (Zone 7a) Moderate season
180 days
Last Spring Frost April 23
180 growing days
First Fall Frost October 20

Petersburg Borough Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (36 days to spare)
Transplant: Apr 16 🍅 Harvest: Jul 16 – Sep 3
Recommended (50%) ✓ Fits season (40 days to spare)
Transplant: Apr 23 🍅 Harvest: Jul 23 – Sep 10
Safe Start (90%) ✓ Fits season (41 days to spare)
Transplant: May 12 🍅 Harvest: Aug 11 – Sep 29

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
0.4″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 471 gal / 100 sq ft
Black Beans needs ~0 GDD — county provides 0 GDD May not mature

Black Beans Planting Timeline โ€” Petersburg Borough, AK

Black Beans Planting Calendar

Activity When Date Range
Direct Sow April 30 Apr 30 โ€“ May 21
Harvest July 30 Jul 30 โ€“ Sep 17

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 7a

Growing Season

180 days

Growing Tips for Petersburg Borough

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 Petersburg Borough, AK?

Petersburg Borough is in Zone 7a with an average last frost of April 23. Plan your Black Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Petersburg Borough, AK?

Petersburg Borough, Alaska is in USDA Hardiness Zone 7a. The average last spring frost is April 23 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Petersburg Borough gardeners in Zone 7a 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 Petersburg Borough, AK. Local conditions may vary. Last updated: April 2026.