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When to Plant Scarlet Runner Beans in Rio Grande County, CO

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.

Rio Grande County, Colorado is in USDA Zone 4b. The average last spring frost is May 31 and the first fall frost is September 19, giving you a growing season of approximately 111 days.

At an elevation of 6,254 feet, Rio Grande County receives approximately 15.8 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Scarlet Runner Beans to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Scarlet Runner Beans successfully. Mulch heavily to conserve soil moisture.

Rio Grande County, CO (Zone 4b) Short season
111 days
Last Spring Frost May 31
111 growing days
First Fall Frost September 19

Rio Grande County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 24 Transplant: Jun 16 🍅 Harvest: Aug 18 – Sep 22
Recommended (50%) ✗ May not fit
Start indoors: Mar 29 Transplant: Jun 21 🍅 Harvest: Aug 23 – Sep 27
Safe Start (90%) ✗ May not fit
Start indoors: Apr 12 Transplant: Jul 5 🍅 Harvest: Sep 6 – Oct 11

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
0.6″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 832 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Scarlet Runner Beans needs ~700 GDD — county provides 1,110 GDD Excellent fit

Scarlet Runner Beans Planting Timeline โ€” Rio Grande County, CO

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 โ€“ Apr 12
Transplant Outdoors June 21 Jun 21 โ€“ Jul 5
Direct Sow June 14 Jun 14 โ€“ Jul 5
Harvest August 23 Aug 23 โ€“ Sep 27

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May โ€”
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
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 4b

Growing Season

111 days

Growing Tips for Rio Grande 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 Rio Grande County, CO?

Rio Grande County is in Zone 4b with an average last frost of May 31. Plan your Scarlet Runner Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Rio Grande County, CO?

Rio Grande County, Colorado is in USDA Hardiness Zone 4b. The average last spring frost is May 31 and first fall frost is September 19.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Rio Grande County gardeners in Zone 4b 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 Rio Grande County, CO. Local conditions may vary. Last updated: April 2026.