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When to Plant Chervil in Arapahoe 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.

Arapahoe County, Colorado is in USDA Zone 5b. The average last spring frost is May 10 and the first fall frost is October 7, giving you a growing season of approximately 150 days.

At an elevation of 7,205 feet, Arapahoe County receives approximately 21.4 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Chervil during the growing season.

Arapahoe County, CO (Zone 5b) Moderate season
150 days
Last Spring Frost May 10
150 growing days
First Fall Frost October 7

Arapahoe 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 (53 days to spare)
Start indoors: Mar 27 Transplant: Apr 24 🍅 Harvest: Jun 5 – Aug 7
Recommended (50%) ✓ Fits season (52 days to spare)
Start indoors: Apr 5 Transplant: May 3 🍅 Harvest: Jun 14 – Aug 16
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Apr 17 Transplant: May 15 🍅 Harvest: Jun 26 – Aug 28

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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 642 gal / 100 sq ft
Drought risk

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

Chervil needs ~762 GDD — county provides 2,287 GDD Excellent fit

Chervil Planting Timeline โ€” Arapahoe County, CO

Chervil Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 โ€“ Apr 19
Transplant Outdoors May 3 May 3 โ€“ May 17
Direct Sow April 26 Apr 26 โ€“ May 17
Fall Sowing July 29 Jul 29 โ€“ Aug 12
Harvest June 14 Jun 14 โ€“ Aug 16

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Fall Sowing Harvest
September โ€”
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 5b

Growing Season

150 days

Growing Tips for Arapahoe 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 Arapahoe County, CO?

Arapahoe County is in Zone 5b with an average last frost of May 10. Plan your Chervil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Arapahoe County, CO?

Arapahoe County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 10 and first fall frost is October 7.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Arapahoe County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Arapahoe County, CO. Local conditions may vary. Last updated: April 2026.