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When to Plant Scarlet Runner Beans in Keweenaw County, MI

Scarlet runner beans are ornamental and edible climbing beans with vivid red flowers that attract hummingbirds. Both the young pods and mature beans are edible.

Keweenaw County, Michigan is in USDA Zone 4a. The average last spring frost is May 19 and the first fall frost is October 1, giving you a growing season of approximately 135 days.

At an elevation of 1,035 feet, Keweenaw County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Scarlet Runner Beans to ensure they mature before fall.

Keweenaw County, MI (Zone 4a) Short season
135 days
Last Spring Frost May 19
135 growing days
First Fall Frost October 1

Keweenaw County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Start indoors: Mar 13 Transplant: Jun 5 🍅 Harvest: Aug 7 – Sep 11
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Mar 17 Transplant: Jun 9 🍅 Harvest: Aug 11 – Sep 15
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 2 Transplant: Jun 25 🍅 Harvest: Aug 27 – Oct 1

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
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Scarlet Runner Beans needs ~752 GDD — county provides 1,451 GDD Excellent fit

Scarlet Runner Beans Planting Timeline โ€” Keweenaw County, MI

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 โ€“ Mar 31
Transplant Outdoors June 9 Jun 9 โ€“ Jun 23
Direct Sow June 2 Jun 2 โ€“ Jun 23
Harvest August 11 Aug 11 โ€“ Sep 15

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April โ€”
May โ€”
June Transplant Outdoors Direct Sow
July โ€”
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

60โ€“80 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

135 days

Growing Tips for Keweenaw County

Provide tall trellising for vigorous vines. Direct sow after frost. Harvest pods young for snap beans or let mature for shelling beans. Tubers are perennial in mild climates.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Level Up Your Garden

Frequently Asked Questions

When should I plant Scarlet Runner Beans in Keweenaw County, MI?

Keweenaw County is in Zone 4a with an average last frost of May 19. Plan your Scarlet Runner Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Keweenaw County, MI?

Keweenaw County, Michigan is in USDA Hardiness Zone 4a. The average last spring frost is May 19 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Keweenaw County gardeners in Zone 4a 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 Keweenaw County, MI. Local conditions may vary. Last updated: April 2026.