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When to Plant Cauliflower in Colusa County, CA

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.

Colusa County, California is in USDA Zone 9a. The average last spring frost is March 6 and the first fall frost is November 28, giving you a growing season of approximately 267 days.

At an elevation of 112 feet, Colusa County receives approximately 29.8 inches of rainfall annually with predominantly loam soil. Summer highs average 94ยฐF, providing good warmth for Cauliflower during the growing season.

Colusa County, CA (Zone 9a) Long season
267 days
Last Spring Frost March 6
267 growing days
First Fall Frost November 28

Colusa County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (151 days to spare)
Start indoors: Jan 26 Transplant: Feb 23 🍅 Harvest: Apr 20 – Jun 22
Recommended (50%) ✓ Fits season (148 days to spare)
Start indoors: Feb 6 Transplant: Mar 6 🍅 Harvest: May 1 – Jul 3
Safe Start (90%) ✓ Fits season (126 days to spare)
Start indoors: Mar 21 Transplant: Apr 18 🍅 Harvest: Jun 13 – Aug 15

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
0.5″/week
You supply
1.8″/week
Watering frequency 2-3 times/week
Season total 4,224 gal / 100 sq ft
Drought risk

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

Cauliflower needs ~1,589 GDD — county provides 5,473 GDD Excellent fit

Cauliflower Planting Timeline โ€” Colusa County, CA

Cauliflower Planting Calendar

Activity When Date Range
Start Indoors February 6 Feb 6 โ€“ Feb 20
Transplant Outdoors March 6 Mar 6 โ€“ Mar 20
Direct Sow February 13 Feb 13 โ€“ Mar 6
Fall Sowing October 3 Oct 3 โ€“ Oct 17
Harvest May 1 May 1 โ€“ Jul 3

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors Direct Sow
March Transplant Outdoors Direct Sow
April โ€”
May Harvest
June Harvest
July Harvest
August โ€”
September โ€”
October Fall Sowing
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 9a

Growing Season

267 days

Growing Tips for Colusa 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

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Frequently Asked Questions

When should I plant Cauliflower in Colusa County, CA?

Colusa County is in Zone 9a with an average last frost of March 6. Plan your Cauliflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Colusa County, CA?

Colusa County, California is in USDA Hardiness Zone 9a. The average last spring frost is March 6 and first fall frost is November 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Colusa County gardeners in Zone 9a 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 Colusa County, CA. Local conditions may vary. Last updated: April 2026.