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When to Plant Chervil in Costilla County, CO

Chervil is a delicate herb with a subtle anise-parsley flavor, essential in French cuisine as part of fines herbes. It prefers cool conditions and partial shade.

Costilla County, Colorado is in USDA Zone 5a. The average last spring frost is June 8 and the first fall frost is September 16, giving you a growing season of approximately 100 days.

At an elevation of 5,598 feet, Costilla County receives approximately 21 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Chervil during the growing season.

Costilla County, CO (Zone 5a) Short season
100 days
Last Spring Frost June 8
100 growing days
First Fall Frost September 16

Costilla County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (6 days to spare)
Start indoors: Apr 25 Transplant: May 23 🍅 Harvest: Jul 4 – Sep 5
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: May 4 Transplant: Jun 1 🍅 Harvest: Jul 13 – Sep 14
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: May 15 Transplant: Jun 12 🍅 Harvest: Jul 24 – Sep 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
0.5″/week
Watering frequency 1-2 times/week
Season total 446 gal / 100 sq ft
Drought risk

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

Chervil needs ~725 GDD — county provides 1,450 GDD Excellent fit

Chervil Planting Timeline โ€” Costilla County, CO

Chervil Planting Calendar

Activity When Date Range
Start Indoors May 4 May 4 โ€“ May 18
Transplant Outdoors June 1 Jun 1 โ€“ Jun 15
Direct Sow May 25 May 25 โ€“ Jun 15
Fall Sowing July 8 Jul 8 โ€“ Jul 22
Harvest July 13 Jul 13 โ€“ Sep 14

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 Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

40โ€“60 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

100 days

Growing Tips for Costilla County

Direct sow in early spring or fall as chervil bolts in heat. Provide shade and cool conditions. Harvest outer leaves as needed; use fresh as it loses flavor when dried.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Chervil in Costilla County, CO?

Costilla County is in Zone 5a with an average last frost of June 8. Plan your Chervil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Costilla County, CO?

Costilla County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 8 and first fall frost is September 16.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Costilla County gardeners in Zone 5a 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 Costilla County, CO. Local conditions may vary. Last updated: April 2026.