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When to plant Scarlet Runner Beans in Knox County County,

Knox County County sits in USDA Zone 5b. Plant Scarlet Runner Beans between April 24 (after last frost on April 17) and May 15.

When to Plant Scarlet Runner Beans in Knox County, IL

Knox County, Illinois Zone 5b June

Top priorities for Knox County, Illinois gardeners in June

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Knox County, Illinois.

Avg. last frost April 17
Avg. first frost October 15
Soil temp (4") 67°F
Watering Moderate
Pest pressure High
Daylight 14.9 hrs
  1. Begin indoor sowing: scarlet runner beans

    These need a head start before your last frost (April 17). Sow into cells now so you're ready to transplant in a few weeks.

Before July arrives, get these ready
  • 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.

Knox County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.

At an elevation of 1,301 feet, Knox County receives approximately 33.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Scarlet Runner Beans to ensure they mature before fall.

Knox County, IL (Zone 5b) Moderate season
181 days
Last Spring Frost April 17
181 growing days
First Fall Frost October 15
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Knox County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.8

Drainage

Well Drained

Scarlet Runner Beans Planting Risk Windows

Early Start (70% safe) ✓ Fits season (69 days to spare)
Start indoors: Feb 15 Transplant: Apr 26 🍅 Harvest: Jun 28 – Aug 2
Recommended (50%) ✓ Fits season (69 days to spare)
Start indoors: Feb 20 Transplant: May 1 🍅 Harvest: Jul 3 – Aug 7
Safe Start (90%) ✓ Fits season (73 days to spare)
Start indoors: Mar 8 Transplant: May 17 🍅 Harvest: Jul 19 – Aug 23

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 Knox County

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

Soil pH

Your soil pH (6.0–6.8) is within Scarlet Runner Beans's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — 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

3
successive plantings in your 181-day season

Sow every 6.9 weeks. Last sowing by Jul 27 to harvest before frost.

Scarlet Runner Beans Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 444 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 3.6" 0.7" 💧 Light watering
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.6" 1.7" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Knox 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 2,353 GDD Excellent fit

Scarlet Runner Beans Planting Timeline — Knox County, IL

Scarlet Runner Beans Planting Calendar

Activity When Date Range
Start Indoors February 20 Feb 20 – Mar 6
Transplant Outdoors May 1 May 1 – May 15
Direct Sow April 24 Apr 24 – May 15
Harvest July 3 Jul 3 – Aug 7

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September
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: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

181 days in Knox County

Growing Tips for Scarlet Runner Beans in Knox County

Direct sow Scarlet Runner Beans outdoors after April 17 in Knox 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 Knox County, IL?

Knox County is in Zone 5b with an average last frost of April 17. Plan your Scarlet Runner Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Knox County, IL?

Knox County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 15.

When should I plant Scarlet Runner Beans in Knox County County, ?

In Knox County County, , plant Scarlet Runner Beans after the last frost (around April 17) and before the first frost (around October 15). Best results when soil holds above 50°F.

What growing zone is Knox County County, for Scarlet Runner Beans?

Knox County County sits in USDA Zone 5b. Scarlet Runner Beans grows reliably in zones 3a through 11b, so it's a good fit here.

Can Scarlet Runner Beans grow in Knox County County's climate?

Yes — Scarlet Runner Beans grows well in Knox County County's temperate climate. Knox County County averages a 181-day frost-free season, with last frost around April 17 and first frost around October 15.

🌱

Your Knox County Garden Planner — Free

A 22-page printable planner built for Knox County (Zone 5b). 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 Knox County, IL. 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.