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When to Plant Yard Long Beans in DeKalb County, IL

DeKalb County, Illinois Zone 5b May

DeKalb County, Illinois gardeners: here's your May plan

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

Avg. last frost April 22
Avg. first frost October 16
Soil temp (4") 56°F
Watering Moderate
Pest pressure Low
Daylight 14.4 hrs
  1. Transplant yard long beans outside

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

To set up a strong June, finish these tasks
  • Starting indoors: yard long beans

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Yard long beans are a tropical legume that produces slender pods up to 24 inches long. They are a staple in Southeast Asian cooking and thrive in hot weather.

DeKalb County, Illinois is in USDA Zone 5b. The average last spring frost is April 22 and the first fall frost is October 16, giving you a growing season of approximately 177 days.

At an elevation of 1,332 feet, DeKalb County receives approximately 34.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Yard Long Beans during the growing season.

DeKalb County, IL (Zone 5b) Moderate season
177 days
Last Spring Frost April 22
177 growing days
First Fall Frost October 16
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DeKalb County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (66 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jun 25 – Aug 6
Recommended (50%) ✓ Fits season (65 days to spare)
Start indoors: Feb 25 Transplant: May 6 🍅 Harvest: Jul 1 – Aug 12
Safe Start (90%) ✓ Fits season (62 days to spare)
Start indoors: Mar 14 Transplant: May 23 🍅 Harvest: Jul 18 – Aug 29

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 DeKalb County

How your county's soil matches Yard Long Beans's growing requirements.

Soil pH

Your soil pH (6.2–7.2) is within Yard Long Beans's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in DeKalb County is excellent for Yard Long Beans — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Yard Long Beans.

Organic Matter

Organic matter is excellent (5.1%) — Yard Long Beans will thrive.

How to Plant Yard Long Beans

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

Succession Planting Yard Long Beans

3
successive plantings in your 177-day season

Sow every 6.3 weeks. Last sowing by Jul 28 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 919 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Yard Long Beans

Yard Long 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 Yard Long Beans Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

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

Yard Long 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.

Yard Long Beans needs ~1,029 GDD — county provides 2,699 GDD Excellent fit

Yard Long Beans Planting Timeline — DeKalb County, IL

Yard Long Beans Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 – Mar 11
Transplant Outdoors May 6 May 6 – May 20
Direct Sow April 29 Apr 29 – May 20
Harvest July 1 Jul 1 – Aug 12

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 · 1-2 times/week

📅 Days to Maturity

55–80 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

177 days in DeKalb County

Growing Tips for Yard Long Beans in DeKalb County

Direct sow Yard Long Beans outdoors after April 22 in DeKalb County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow after soil is warm. Provide tall poles or trellising as vines can reach 8-10 feet. Harvest when pods are pencil-thick before seeds bulge. Cook quickly for best texture.

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 Yard Long Beans in DeKalb County, IL?

DeKalb County is in Zone 5b with an average last frost of April 22. Plan your Yard Long Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is DeKalb County, IL?

DeKalb County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 22 and first fall frost is October 16.

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Your DeKalb County Garden Planner — Free

A 24-page printable planner built for DeKalb 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 DeKalb County, IL. 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.