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When to Plant Scarlet Runner Beans in Custer County, SD

Custer County, South Dakota Zone 5a June

This month in Custer County, South Dakota

June is a pivotal month for Custer County, South Dakota gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 14
Avg. first frost October 2
Soil temp (4") 66°F
Watering High
Pest pressure High
Daylight 15.2 hrs
July prep starts now
  • 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.

Custer County, South Dakota is in USDA Zone 5a. The average last spring frost is May 14 and the first fall frost is October 2, giving you a growing season of approximately 141 days.

At an elevation of 868 feet, Custer County receives approximately 29.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Scarlet Runner Beans to ensure they mature before fall.

Custer County, SD (Zone 5a) Short season
141 days
Last Spring Frost May 14
141 growing days
First Fall Frost October 2
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Custer County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.5

Drainage

Well Drained

Scarlet Runner Beans Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Mar 15 Transplant: May 24 🍅 Harvest: Jul 26 – Aug 30
Recommended (50%) ✓ Fits season (29 days to spare)
Start indoors: Mar 19 Transplant: May 28 🍅 Harvest: Jul 30 – Sep 3
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Mar 29 Transplant: Jun 7 🍅 Harvest: Aug 9 – Sep 13

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 Custer County

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

Soil pH

Your soil pH (6.7–7.5) is more alkaline than Scarlet Runner Beans prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). 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

2
successive plantings in your 141-day season

Sow every 6.9 weeks. Last sowing by Jul 14 to harvest before frost.

Scarlet Runner Beans Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 187 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

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 2.2" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.1" 1.2" 💧 Light watering
Jun 4.3" 2.1" 2.2" 🚿 Regular watering
Jul 4.3" 2.4" 1.9" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.5" 1.8" 💧 Light watering
Oct 4.3" 2.4" 1.9" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Custer 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 ~910 GDD — county provides 1,833 GDD Excellent fit

Scarlet Runner Beans Planting Timeline — Custer County, SD

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors May 28 May 28 – Jun 11
Direct Sow May 21 May 21 – Jun 11
Harvest July 30 Jul 30 – Sep 3

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

141 days in Custer County

Growing Tips for Scarlet Runner Beans in Custer County

Direct sow Scarlet Runner Beans outdoors after May 14 in Custer 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 Custer County, SD?

Custer County is in Zone 5a with an average last frost of May 14. Plan your Scarlet Runner Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Custer County, SD?

Custer County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is May 14 and first fall frost is October 2.

🌱

Your Custer County Garden Planner — Free

A 22-page printable planner built for Custer County (Zone 5a). 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 Custer County, SD. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.