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When to Plant Scarlet Runner Beans in Brown County, SD

Brown County, South Dakota Zone 4a May

May in Brown County, South Dakota — your action list

Each item below is timed to Brown County, South Dakota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 8
Avg. first frost October 4
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs
  1. Time to transplant scarlet runner beans

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Plant scarlet runner beans from seed, right in the garden

    These tolerate cool soil, so you're not gambling by sowing now.

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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.

Brown County, South Dakota is in USDA Zone 4a. The average last spring frost is May 8 and the first fall frost is October 4, giving you a growing season of approximately 149 days.

At an elevation of 536 feet, Brown County receives approximately 34.7 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.

Brown County, SD (Zone 4a) Short season
149 days
Last Spring Frost May 8
149 growing days
First Fall Frost October 4

Brown County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (31 days to spare)
Start indoors: Feb 26 Transplant: May 21 🍅 Harvest: Jul 23 – Aug 27
Recommended (50%) ✓ Fits season (30 days to spare)
Start indoors: Mar 6 Transplant: May 29 🍅 Harvest: Jul 31 – Sep 4
Safe Start (90%) ✓ Fits season (31 days to spare)
Start indoors: Mar 16 Transplant: Jun 8 🍅 Harvest: Aug 10 – Sep 14

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 Brown County

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

Soil pH

Your soil pH (6.3–7.6) overlaps with Scarlet Runner Beans's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — Scarlet Runner Beans will thrive.

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 149-day season

Sow every 6.9 weeks. Last sowing by Jul 16 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 29 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 0.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.3" 5.1" 0" ✅ Rainfall sufficient
Jun 4.3" 5.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 2.4" 1.9" 💧 Light watering
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Brown 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 1,937 GDD Excellent fit

Scarlet Runner Beans Planting Timeline — Brown County, SD

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 – Mar 20
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 22 May 22 – Jun 12
Harvest July 31 Jul 31 – Sep 4

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

Month-by-Month Timeline

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

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: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

149 days in Brown County

Growing Tips for Scarlet Runner Beans in Brown County

Direct sow Scarlet Runner Beans outdoors after May 08 in Brown 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 Brown County, SD?

Brown County is in Zone 4a with an average last frost of May 8. Plan your Scarlet Runner Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Brown County, SD?

Brown County, South Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 8 and first fall frost is October 4.

🌱

Your Brown County Garden Planner — Free

A 24-page printable planner built for Brown County (Zone 4a). 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 Brown County, SD. 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.