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When to Plant Tarragon in Jefferson County, IL

French tarragon is a perennial herb with slender leaves and a distinctive anise-like flavor essential in French cooking. It does not produce viable seed and must be propagated vegetatively.

Jefferson County, Illinois is in USDA Zone 6a. 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 509 feet, Jefferson County receives approximately 34 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Tarragon during the growing season.

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

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Transplant: Apr 11 🍅 Harvest: Jun 13 – Aug 22
Recommended (50%) ✓ Fits season (54 days to spare)
Transplant: Apr 16 🍅 Harvest: Jun 18 – Aug 27
Safe Start (90%) ✓ Fits season (57 days to spare)
Transplant: Apr 26 🍅 Harvest: Jun 28 – Sep 6

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
0.3″/week
Watering frequency 1-2 times/week
Season total 547 gal / 100 sq ft
Drought risk

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

Tarragon needs ~1,200 GDD — county provides 3,104 GDD Excellent fit

Tarragon Planting Timeline โ€” Jefferson County, IL

Tarragon Planting Calendar

Activity When Date Range
Transplant Outdoors April 16 Apr 16 โ€“ Apr 30
Harvest June 18 Jun 18 โ€“ Aug 27

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May โ€”
June Harvest
July Harvest
August 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

6 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

194 days

Growing Tips for Jefferson County

Purchase plants or divisions as French tarragon does not grow true from seed. Plant in well-drained soil. Divide every 3-4 years to maintain vigor. Harvest tips regularly for best flavor.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Tarragon in Jefferson County, IL?

Jefferson County is in Zone 6a with an average last frost of April 9. Plan your Tarragon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jefferson County, IL?

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

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Plan Your Garden with Confidence

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