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When to Plant Celery in Williamson County, IL

Celery is a marshland plant that requires consistent moisture and cool temperatures to produce crisp, flavorful stalks. It is a rewarding but demanding garden crop.

Williamson County, Illinois is in USDA Zone 6b. 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 91ยฐF, providing good warmth for Celery during the growing season.

Williamson County, IL (Zone 6b) Moderate season
193 days
Last Spring Frost April 10
193 growing days
First Fall Frost October 20

Williamson 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 (51 days to spare)
Start indoors: Mar 1 Transplant: Apr 5 🍅 Harvest: Jun 28 – Aug 23
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Mar 6 Transplant: Apr 10 🍅 Harvest: Jul 3 – Aug 28
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Mar 18 Transplant: Apr 22 🍅 Harvest: Jul 15 – Sep 9

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.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,369 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Celery needs ~1,825 GDD — county provides 3,522 GDD Excellent fit

Celery Planting Timeline โ€” Williamson County, IL

Celery Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 โ€“ Mar 20
Transplant Outdoors April 10 Apr 10 โ€“ Apr 24
Direct Sow March 27 Mar 27 โ€“ Apr 17
Fall Sowing August 11 Aug 11 โ€“ Aug 25
Harvest July 3 Jul 3 โ€“ Aug 28

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6b

Growing Season

193 days

Growing Tips for Williamson County

Start seeds indoors 10-12 weeks before last frost. Keep soil consistently moist and never let it dry out. Blanch stalks by mounding soil or using collars for milder flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Level Up Your Garden

Frequently Asked Questions

When should I plant Celery in Williamson County, IL?

Williamson County is in Zone 6b with an average last frost of April 10. Plan your Celery planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Williamson County, IL?

Williamson County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 10 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Williamson County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

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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 Williamson County, IL. Local conditions may vary. Last updated: April 2026.