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When to Plant Fennel (herb) in Saline County, IL

Herb fennel is grown for its aromatic leaves, stalks, and seeds rather than a bulb. It has a strong anise flavor and its flowers attract beneficial insects.

Saline County, Illinois is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 24, giving you a growing season of approximately 199 days.

At an elevation of 748 feet, Saline County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Fennel (herb) during the growing season.

Saline County, IL (Zone 6b) Moderate season
199 days
Last Spring Frost April 8
199 growing days
First Fall Frost October 24

Saline County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (70 days to spare)
Start indoors: Feb 28 Transplant: Mar 28 🍅 Harvest: May 30 – Aug 8
Recommended (50%) ✓ Fits season (73 days to spare)
Start indoors: Mar 4 Transplant: Apr 1 🍅 Harvest: Jun 3 – Aug 12
Safe Start (90%) ✓ Fits season (80 days to spare)
Start indoors: Mar 17 Transplant: Apr 14 🍅 Harvest: Jun 16 – Aug 25

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
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 235 gal / 100 sq ft
Fennel (herb) needs ~1,200 GDD — county provides 3,184 GDD Excellent fit

Fennel (herb) Planting Timeline โ€” Saline County, IL

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 โ€“ Mar 18
Transplant Outdoors April 1 Apr 1 โ€“ Apr 15
Direct Sow March 25 Mar 25 โ€“ Apr 15
Fall Sowing August 15 Aug 15 โ€“ Aug 29
Harvest June 3 Jun 3 โ€“ Aug 12

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 Harvest
July Harvest
August Fall Sowing Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 6b

Growing Season

199 days

Growing Tips for Saline County

Direct sow in spring or fall. Unlike Florence fennel, herb fennel does not form a bulb. Harvest fronds as needed and seeds when they turn brown. Self-sows readily.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers
  • Green Beans

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Frequently Asked Questions

When should I plant Fennel (herb) in Saline County, IL?

Saline County is in Zone 6b with an average last frost of April 8. Plan your Fennel (herb) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Saline County, IL?

Saline County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 24.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Saline 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 Saline County, IL. Local conditions may vary. Last updated: April 2026.