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When to Plant Crosne in Douglas County, CO

Douglas County, Colorado Zone 5b May

What to do in May

Each item below is timed to Douglas County, Colorado's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 22
Avg. first frost September 20
Soil temp (4") 35°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Put crosne seeds straight in the ground

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

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Crosne (Chinese artichoke) produces small, segmented white tubers with a crunchy texture and mild artichoke-nutty flavor. They are a rare delicacy in French cuisine.

Douglas County, Colorado is in USDA Zone 5b. The average last spring frost is May 22 and the first fall frost is September 20, giving you a growing season of approximately 121 days.

At an elevation of 7,421 feet, Douglas County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Crosne during the growing season. With low rainfall, drip irrigation is essential for growing Crosne successfully. Mulch heavily to conserve soil moisture.

Douglas County, CO (Zone 5b) Short season
121 days
Last Spring Frost May 22
121 growing days
First Fall Frost September 20
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Douglas County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 12 🍅 Harvest: Oct 13 – Oct 27
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Oct 23 – Nov 6
Safe Start (90%) ✗ May not fit
Transplant: Jun 19 🍅 Harvest: Nov 20 – Dec 4

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.

Soil Compatibility in Douglas County

How your county's soil matches Crosne's growing requirements.

Soil pH

Your soil pH (6.7–8.4) is more alkaline than Crosne prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Douglas County is excellent for Crosne — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Crosne.

How to Plant Crosne

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 714 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Crosne

Crosne needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Crosne Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 4.3" 1.4" 2.9" 🚿 Regular watering
Jun 4.3" 1" 3.3" 🚿 Regular watering
Jul 4.3" 1" 3.3" 🚿 Regular watering
Aug 4.3" 1.4" 2.9" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Douglas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Crosne Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Crosne needs ~2,406 GDD — county provides 1,663 GDD May not mature

Crosne Planting Timeline — Douglas County, CO

Crosne Planting Calendar

Activity When Date Range
Direct Sow May 8 May 8 – May 29
Harvest October 9 Oct 9 – Oct 23
Fall Sowing July 12 Jul 12 – Jul 26

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Direct Sow
June
July Fall Sowing
August
September
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

150–200 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

121 days in Douglas County

Growing Tips for Crosne in Douglas County

Direct sow Crosne outdoors after May 22 in Douglas County when soil has warmed and frost danger has passed.

Your 121.0-day growing season in Douglas County is tight for Crosne (150.0-200.0 days to maturity). Start indoors and choose early-maturing varieties.

Douglas County receives only 13" of rain annually. Crosne needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant tubers 3 inches deep in spring. Mark the location well as plants die back. Harvest in late fall after frost. Leave some tubers in ground for next year. Very labor-intensive to harvest.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Crosne in Douglas County, CO?

Douglas County is in Zone 5b with an average last frost of May 22. Plan your Crosne planting based on this frost date — see the calendar above for exact timing.

What planting zone is Douglas County, CO?

Douglas County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 22 and first fall frost is September 20.

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Your Douglas County Garden Planner — Free

A 24-page printable planner built for Douglas County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Douglas County, CO. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.