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When to Plant Tarragon in Gunnison County, CO

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.

Gunnison County, Colorado is in USDA Zone 4a. The average last spring frost is June 12 and the first fall frost is September 10, giving you a growing season of approximately 90 days.

At an elevation of 7,435 feet, Gunnison County receives approximately 17.9 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Tarragon to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Tarragon successfully. Mulch heavily to conserve soil moisture.

Gunnison County, CO (Zone 4a) Very short season
90 days
Last Spring Frost June 12
90 growing days
First Fall Frost September 10

Gunnison County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Jun 5 🍅 Harvest: Aug 7 – Oct 16
Recommended (50%) ✗ May not fit
Transplant: Jun 19 🍅 Harvest: Aug 21 – Oct 30
Safe Start (90%) ✗ May not fit
Transplant: Jul 2 🍅 Harvest: Sep 3 – Nov 12

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
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 158 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Tarragon needs ~919 GDD — county provides 1,102 GDD Good fit

Tarragon Planting Timeline โ€” Gunnison County, CO

Tarragon Planting Calendar

Activity When Date Range
Transplant Outdoors June 19 Jun 19 โ€“ Jul 3
Harvest August 21 Aug 21 โ€“ Oct 30

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June Transplant Outdoors
July Transplant Outdoors
August Harvest
September Harvest
October Harvest
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 4a

Growing Season

90 days

Growing Tips for Gunnison 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 Gunnison County, CO?

Gunnison County is in Zone 4a with an average last frost of June 12. Plan your Tarragon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Gunnison County, CO?

Gunnison County, Colorado is in USDA Hardiness Zone 4a. The average last spring frost is June 12 and first fall frost is September 10.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Gunnison County gardeners in Zone 4a 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 Gunnison County, CO. Local conditions may vary. Last updated: April 2026.