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When to Plant Butternut Squash in Colusa County, CA

Butternut squash is a popular winter squash with a long neck, small seed cavity, and sweet, nutty orange flesh. It stores exceptionally well for months.

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 Butternut Squash 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 (137 days to spare)
Start indoors: Jan 26 Transplant: Mar 2 🍅 Harvest: Jun 1 – Jul 6
Recommended (50%) ✓ Fits season (134 days to spare)
Start indoors: Feb 6 Transplant: Mar 13 🍅 Harvest: Jun 12 – Jul 17
Safe Start (90%) ✓ Fits season (112 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jul 25 – Aug 29

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
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,370 gal / 100 sq ft
Drought risk

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

Butternut Squash needs ~1,999 GDD — county provides 5,473 GDD Excellent fit

Butternut Squash Planting Timeline โ€” Colusa County, CA

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors February 6 Feb 6 โ€“ Feb 20
Transplant Outdoors March 13 Mar 13 โ€“ Mar 27
Direct Sow March 6 Mar 6 โ€“ Mar 27
Harvest June 12 Jun 12 โ€“ Jul 17

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Transplant Outdoors Direct Sow
April โ€”
May โ€”
June Harvest
July Harvest
August โ€”
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

85โ€“110 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 9a

Growing Season

267 days

Growing Tips for Colusa County

Start seeds indoors 3 weeks early or direct sow after frost. Allow 6-8 feet for sprawling vines. Harvest when the skin is hard and uniformly tan. Cure in the sun for 10 days.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Butternut Squash in Colusa County, CA?

Colusa County is in Zone 9a with an average last frost of March 6. Plan your Butternut Squash 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.