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When to Plant Cauliflower in Costilla County, CO

Cauliflower is a cool-season brassica that produces dense white, purple, or green heads called curds. It is more finicky than broccoli but rewards with a mild, nutty flavor.

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 Cauliflower 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) ✗ May not fit
Start indoors: Apr 25 Transplant: May 30 🍅 Harvest: Jul 25 – Sep 26
Recommended (50%) ✗ May not fit
Start indoors: May 4 Transplant: Jun 8 🍅 Harvest: Aug 3 – Oct 5
Safe Start (90%) ✗ May not fit
Start indoors: May 15 Transplant: Jun 19 🍅 Harvest: Aug 14 – Oct 16

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
1.5″/week
Rainfall provides
0.9″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 1,141 gal / 100 sq ft
Drought risk

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

Cauliflower needs ~1,124 GDD — county provides 1,450 GDD Good fit

Cauliflower Planting Timeline โ€” Costilla County, CO

Cauliflower Planting Calendar

Activity When Date Range
Start Indoors May 4 May 4 โ€“ May 18
Transplant Outdoors June 8 Jun 8 โ€“ Jun 22
Direct Sow May 25 May 25 โ€“ Jun 15
Fall Sowing July 8 Jul 8 โ€“ Jul 22
Harvest August 3 Aug 3 โ€“ Oct 5

Plant 1" deep ยท 15" apart ยท Rows 24" 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
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

55โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

100 days

Growing Tips for Costilla County

Start seeds indoors 6 weeks before transplanting. Blanch white varieties by tying outer leaves over the head. Provide consistent moisture and avoid temperature extremes.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Cauliflower in Costilla County, CO?

Costilla County is in Zone 5a with an average last frost of June 8. Plan your Cauliflower 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.

๐ŸŒฑ

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.