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When to Plant Sorrel in Contra Costa County, CA

Sorrel is a perennial herb with tangy, lemon-flavored arrow-shaped leaves. It is one of the first greens to emerge in spring and is used in soups and salads.

Contra Costa County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 29, giving you a growing season of approximately 276 days.

At an elevation of 88 feet, Contra Costa County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 93ยฐF, providing good warmth for Sorrel during the growing season. With low rainfall, drip irrigation is essential for growing Sorrel successfully. Mulch heavily to conserve soil moisture.

Contra Costa County, CA (Zone 9b) Year-round
276 days
Last Spring Frost February 26
276 growing days
First Fall Frost November 29

Contra Costa County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (193 days to spare)
Start indoors: Jan 8 Transplant: Jan 29 🍅 Harvest: Mar 12 – May 14
Recommended (50%) ✓ Fits season (178 days to spare)
Start indoors: Jan 29 Transplant: Feb 19 🍅 Harvest: Apr 2 – Jun 4
Safe Start (90%) ✓ Fits season (163 days to spare)
Start indoors: Mar 5 Transplant: Mar 26 🍅 Harvest: May 7 – Jul 9

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
0.3″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,106 gal / 100 sq ft
Drought risk

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

Sorrel needs ~988 GDD — county provides 5,470 GDD Excellent fit

Sorrel Planting Timeline โ€” Contra Costa County, CA

Sorrel Planting Calendar

Activity When Date Range
Start Indoors January 29 Jan 29 โ€“ Feb 12
Transplant Outdoors February 19 Feb 19 โ€“ Mar 5
Direct Sow February 5 Feb 5 โ€“ Feb 26
Fall Sowing October 4 Oct 4 โ€“ Oct 18
Harvest April 2 Apr 2 โ€“ Jun 4

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

Month-by-Month Timeline

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

5.5 โ€“ 7

USDA Zone

Zone 9b

Growing Season

276 days

Growing Tips for Contra Costa County

Direct sow in early spring or fall. Remove flower stalks promptly to encourage leaf production. Divide clumps every 3-4 years. Young leaves have the best flavor.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Sorrel in Contra Costa County, CA?

Contra Costa County is in Zone 9b with an average last frost of February 26. Plan your Sorrel planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Contra Costa County, CA?

Contra Costa County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 29.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Contra Costa County gardeners in Zone 9b organize planting dates, track what's growing, and never miss a planting window.

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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 Contra Costa County, CA. Local conditions may vary. Last updated: April 2026.