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When to Plant Chard in Washington County, IL

Washington County, Illinois Zone 6b May

What to do in May

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

Avg. last frost April 9
Avg. first frost October 20
Soil temp (4") 62°F
Watering Moderate
Pest pressure Low
Daylight 14.1 hrs
  1. Fire up the seed-starting tray: chard

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

A few tasks this May that'll pay off in June
  • First harvests: chard

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Swiss chard is a colorful, heat-tolerant green with large crinkled leaves and vibrant stalks in red, yellow, and white. Both the leaves and stems are edible and nutritious.

Washington County, Illinois is in USDA Zone 6b. The average last spring frost is April 9 and the first fall frost is October 20, giving you a growing season of approximately 194 days.

At an elevation of 1,126 feet, Washington County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Chard during the growing season.

Washington County, IL (Zone 6b) Moderate season
194 days
Last Spring Frost April 9
194 growing days
First Fall Frost October 20

Washington County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (86 days to spare)
Start indoors: Feb 28 Transplant: Apr 4 🍅 Harvest: May 30 – Jul 18
Recommended (50%) ✓ Fits season (89 days to spare)
Start indoors: Mar 5 Transplant: Apr 9 🍅 Harvest: Jun 4 – Jul 23
Safe Start (90%) ✓ Fits season (89 days to spare)
Start indoors: Mar 15 Transplant: Apr 19 🍅 Harvest: Jun 14 – Aug 2

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 Washington County

How your county's soil matches Chard's growing requirements.

Soil pH

Your soil pH (5.9–7.2) overlaps with Chard's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Washington County is excellent for Chard — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Chard.

How to Plant Chard

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Chard

4
successive plantings in your 194-day season

Sow every 5.7 weeks. Last sowing by Aug 21 to harvest before frost.

For a dedicated fall crop, sow by Aug 11.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 122 gal / 100 sq ft

Monthly Watering Guide for Chard

Chard needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Chard Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.5" 3.7" 0" ✅ Rainfall sufficient
May 3.5" 3.4" 0.1" 💧 Light watering
Jun 3.5" 4.3" 0" ✅ Rainfall sufficient
Jul 3.5" 3.9" 0" ✅ Rainfall sufficient
Aug 3.5" 3.8" 0" ✅ Rainfall sufficient
Sep 3.5" 2.8" 0.7" 💧 Light watering
Oct 3.5" 2.5" 1" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Chard 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.

Chard needs ~839 GDD — county provides 2,958 GDD Excellent fit

Chard Planting Timeline — Washington County, IL

Chard Planting Calendar

Activity When Date Range
Start Indoors March 5 Mar 5 – Mar 19
Transplant Outdoors April 9 Apr 9 – Apr 23
Direct Sow March 26 Mar 26 – Apr 16
Harvest June 4 Jun 4 – Jul 23
Fall Sowing August 11 Aug 11 – Aug 25

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

194 days in Washington County

Growing Tips for Chard in Washington County

Direct sow Chard outdoors after April 09 in Washington County when soil has warmed and frost danger has passed.

General growing tips

Direct sow or transplant after last frost. Harvest outer leaves regularly to encourage continuous production. Chard tolerates both heat and light frost.

Companion Planting

Good Companions

Avoid Planting Near

  • Corn
  • Cucumbers

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Chard in Washington County, IL?

Washington County is in Zone 6b with an average last frost of April 9. Plan your Chard planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington County, IL?

Washington County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 9 and first fall frost is October 20.

🌱

Your Washington County Garden Planner — Free

A 24-page printable planner built for Washington 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 Washington 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.