When to Plant Chard in Williamson County, IL
May in the garden — Williamson County, Illinois
Welcome to May in Zone 7a. These are the moves that will have the biggest impact on your growing season.
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Indoor seed-starting week for chard
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
Coming up in June — start thinking about
- First harvests: chard
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.
Williamson County, Illinois is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.
At an elevation of 1,253 feet, Williamson County receives approximately 38.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Chard during the growing season.
Williamson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.2
Drainage
Well Drained
Plant Planting Risk Windows
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 Williamson County
How your county's soil matches Chard's growing requirements.
Soil pH
Your soil pH (6.2–7.2) overlaps with Chard's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Williamson County is excellent for Chard — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.4%) — Chard will thrive.
How to Plant Chard
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Chard
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
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | 3.5" | 4" | 0" | ✅ Rainfall sufficient |
| May | 3.5" | 4.9" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 4.3" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 3.7" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 3.2" | 0.3" | 💧 Light watering |
| Oct | 3.5" | 2.9" | 0.6" | 💧 Light watering |
| Nov | — | 2.4" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Williamson 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 Planting Timeline — Williamson County, IL
Chard Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 6 | Mar 6 – Mar 20 |
| Transplant Outdoors | April 10 | Apr 10 – Apr 24 |
| Direct Sow | March 27 | Mar 27 – Apr 17 |
| Harvest | June 5 | Jun 5 – Jul 24 |
| Fall Sowing | August 11 | Aug 11 – Aug 25 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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 · Natural rainfall sufficient
📅 Days to Maturity
50–60 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
193 days in Williamson County
Growing Tips for Chard in Williamson County
Direct sow Chard outdoors after April 10 in Williamson County when soil has warmed and frost danger has passed.
Summer highs in Williamson County reach 91°F — grow Chard as a spring or fall crop. Use shade cloth if planting in summer.
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
Check more plant combinations with our Companion Planting Checker →
Chard in Other Locations
Frequently Asked Questions
When should I plant Chard in Williamson County, IL?
Williamson County is in Zone 7a with an average last frost of April 10. Plan your Chard planting based on this frost date — see the calendar above for exact timing.
What planting zone is Williamson County, IL?
Williamson County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 20.
Your Williamson County Garden Planner — Free
A 24-page printable planner built for Williamson County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.