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When to Plant Scarlet Runner Beans in St. Clair County, MO

St. Clair County, Missouri Zone 6b May

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Avg. last frost April 8
Avg. first frost October 26
Soil temp (4") 65°F
Watering Low
Pest pressure Low
Daylight 14.1 hrs
Get ahead of June
  • Starting indoors: scarlet runner beans
  • First harvests: scarlet runner beans

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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.

St. Clair County, Missouri is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 26, giving you a growing season of approximately 201 days.

At an elevation of 699 feet, St. Clair County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Scarlet Runner Beans during the growing season.

St. Clair County, MO (Zone 6b) Long season
201 days
Last Spring Frost April 8
201 growing days
First Fall Frost October 26

St. Clair County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (89 days to spare)
Start indoors: Feb 4 Transplant: Apr 15 🍅 Harvest: Jun 17 – Jul 22
Recommended (50%) ✓ Fits season (89 days to spare)
Start indoors: Feb 11 Transplant: Apr 22 🍅 Harvest: Jun 24 – Jul 29
Safe Start (90%) ✓ Fits season (89 days to spare)
Start indoors: Feb 22 Transplant: May 3 🍅 Harvest: Jul 5 – Aug 9

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 St. Clair County

How your county's soil matches Scarlet Runner Beans's growing requirements.

Soil pH

Your soil pH (5.5–6.7) overlaps with Scarlet Runner Beans's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in St. Clair County is excellent for Scarlet Runner Beans — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Scarlet Runner Beans.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Scarlet Runner Beans.

How to Plant Scarlet Runner Beans

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

Succession Planting Scarlet Runner Beans

3
successive plantings in your 201-day season

Sow every 6.9 weeks. Last sowing by Aug 07 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Scarlet Runner Beans

Scarlet Runner 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 Scarlet Runner Beans Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 4.3" 0" ✅ Rainfall sufficient
May 4.3" 5.2" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 4.8" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

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

Scarlet Runner 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.

Scarlet Runner Beans needs ~1,225 GDD — county provides 3,517 GDD Excellent fit

Scarlet Runner Beans Planting Timeline — St. Clair County, MO

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors February 11 Feb 11 – Feb 25
Transplant Outdoors April 22 Apr 22 – May 6
Direct Sow April 15 Apr 15 – May 6
Harvest June 24 Jun 24 – Jul 29

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

201 days in St. Clair County

Growing Tips for Scarlet Runner Beans in St. Clair County

Direct sow Scarlet Runner Beans outdoors after April 08 in St. Clair County when soil has warmed and frost danger has passed.

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

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Scarlet Runner Beans in St. Clair County, MO?

St. Clair County is in Zone 6b with an average last frost of April 8. Plan your Scarlet Runner Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Clair County, MO?

St. Clair County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 26.

🌱

Your St. Clair County Garden Planner — Free

A 24-page printable planner built for St. Clair County (Zone 6b). 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 St. Clair County, MO. 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.