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When to Plant Fennel (herb) in Montgomery 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.

Montgomery County, Illinois is in USDA Zone 6a. The average last spring frost is April 13 and the first fall frost is October 21, giving you a growing season of approximately 191 days.

At an elevation of 1,331 feet, Montgomery County receives approximately 30.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Fennel (herb) during the growing season.

Montgomery County, IL (Zone 6a) Moderate season
191 days
Last Spring Frost April 13
191 growing days
First Fall Frost October 21

Montgomery County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (65 days to spare)
Start indoors: Mar 2 Transplant: Mar 30 🍅 Harvest: Jun 1 – Aug 10
Recommended (50%) ✓ Fits season (65 days to spare)
Start indoors: Mar 9 Transplant: Apr 6 🍅 Harvest: Jun 8 – Aug 17
Safe Start (90%) ✓ Fits season (60 days to spare)
Start indoors: Mar 24 Transplant: Apr 21 🍅 Harvest: Jun 23 – Sep 1

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
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,085 gal / 100 sq ft
Fennel (herb) needs ~1,200 GDD — county provides 3,056 GDD Excellent fit

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

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 โ€“ Mar 23
Transplant Outdoors April 6 Apr 6 โ€“ Apr 20
Direct Sow March 30 Mar 30 โ€“ Apr 20
Fall Sowing August 12 Aug 12 โ€“ Aug 26
Harvest June 8 Jun 8 โ€“ Aug 17

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 6a

Growing Season

191 days

Growing Tips for Montgomery 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 Montgomery County, IL?

Montgomery County is in Zone 6a with an average last frost of April 13. Plan your Fennel (herb) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Montgomery County, IL?

Montgomery County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 13 and first fall frost is October 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Montgomery County gardeners in Zone 6a 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 Montgomery County, IL. Local conditions may vary. Last updated: April 2026.