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When to Plant Tomatillo in San Joaquin County, CA

Tomatillos are a Mexican staple that produces tart, green fruits enclosed in papery husks. They are essential for salsa verde and green sauces.

San Joaquin County, California is in USDA Zone 9a. The average last spring frost is February 4 and the first fall frost is December 6, giving you a growing season of approximately 305 days.

At an elevation of 220 feet, San Joaquin County receives approximately 15 inches of rainfall annually with predominantly loam soil. Summer highs average 93ยฐF, providing good warmth for Tomatillo during the growing season. With low rainfall, drip irrigation is essential for growing Tomatillo successfully. Mulch heavily to conserve soil moisture.

San Joaquin County, CA (Zone 9a) Year-round
305 days
Last Spring Frost February 4
305 growing days
First Fall Frost December 6

San Joaquin County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (175 days to spare)
Start indoors: Dec 7 Transplant: Jan 25 🍅 Harvest: Mar 29 – Jun 7
Recommended (50%) ✓ Fits season (165 days to spare)
Start indoors: Dec 24 Transplant: Feb 11 🍅 Harvest: Apr 15 – Jun 24
Safe Start (90%) ✓ Fits season (149 days to spare)
Start indoors: Jan 22 Transplant: Mar 12 🍅 Harvest: May 14 – Jul 23

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
0.2″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,595 gal / 100 sq ft
Drought risk

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

Tomatillo needs ~1,432 GDD — county provides 6,043 GDD Excellent fit

Tomatillo Planting Timeline โ€” San Joaquin County, CA

Tomatillo Planting Calendar

Activity When Date Range
Start Indoors December 24 Dec 24 โ€“ Jan 7
Transplant Outdoors February 11 Feb 11 โ€“ Feb 25
Direct Sow February 4 Feb 4 โ€“ Feb 25
Harvest April 15 Apr 15 โ€“ Jun 24

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“85 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 9a

Growing Season

305 days

Growing Tips for San Joaquin County

Start seeds indoors 6-8 weeks before last frost. Plant at least two plants for cross-pollination. Harvest when fruits fill the husk and it begins to split.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Dill

Level Up Your Garden

Frequently Asked Questions

When should I plant Tomatillo in San Joaquin County, CA?

San Joaquin County is in Zone 9a with an average last frost of February 4. Plan your Tomatillo planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is San Joaquin County, CA?

San Joaquin County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 4 and first fall frost is December 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help San Joaquin 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 San Joaquin County, CA. Local conditions may vary. Last updated: April 2026.