When to Plant Tomatillo in Alameda County, CA
May in Alameda County, California — your action list
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Alameda County, California.
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Start harvesting tomatillo
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Before June arrives, get these ready
- First harvests: tomatillo
Tomatillos are a Mexican staple that produces tart, green fruits enclosed in papery husks. They are essential for salsa verde and green sauces.
Alameda County, California is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 328 days.
At an elevation of 379 feet, Alameda County receives approximately 16.4 inches of rainfall annually with predominantly loam soil. Summer highs average 97°F, so Tomatillo may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Tomatillo successfully. Mulch heavily to conserve soil moisture.
Alameda County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.7
Drainage
Well Drained
Plant Planting Risk Windows
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.
Soil Compatibility in Alameda County
How your county's soil matches Tomatillo's growing requirements.
Soil pH
Your soil pH (6.3–7.7) overlaps with Tomatillo's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Alameda County is excellent for Tomatillo — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Tomatillo.
How to Plant Tomatillo
Succession Planting Tomatillo
Sow every 6.9 weeks. Last sowing by Sep 18 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Tomatillo
Tomatillo needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.
| Month | Tomatillo Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | 4.8" | 3" | 1.8" | 💧 Light watering |
| Feb | 4.8" | 3.6" | 1.2" | 💧 Light watering |
| Mar | 4.8" | 2.6" | 2.2" | 💧 Light watering |
| Apr | 4.8" | 1.2" | 3.6" | 🚿 Regular watering |
| May | 4.8" | 0.4" | 4.4" | 🚿 Regular watering |
| Jun | 4.8" | 0.1" | 4.7" | 🚿 Regular watering |
| Jul | 4.8" | 0" | 4.8" | 🚿 Regular watering |
| Aug | 4.8" | 0" | 4.8" | 🚿 Regular watering |
| Sep | 4.8" | 0.2" | 4.6" | 🚿 Regular watering |
| Oct | 4.8" | 0.6" | 4.2" | 🚿 Regular watering |
| Nov | 4.8" | 1.5" | 3.3" | 🚿 Regular watering |
| Dec | 4.8" | 3.1" | 1.7" | 💧 Light watering |
Water needs are for active growing months only (Jan–Dec in Alameda County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Tomatillo Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Tomatillo Planting Timeline — Alameda County, CA
Tomatillo Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 7 | Dec 7 – Dec 21 |
| Transplant Outdoors | January 25 | Jan 25 – Feb 8 |
| Direct Sow | January 18 | Jan 18 – Feb 8 |
| Harvest | March 29 | Mar 29 – Jun 7 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | Transplant Outdoors Direct Sow |
| March | Harvest |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | Start Indoors |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.1"/week · 2-3 times/week
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
328 days in Alameda County
Growing Tips for Tomatillo in Alameda County
Direct sow Tomatillo outdoors after January 18 in Alameda County when soil has warmed and frost danger has passed.
With summer highs reaching 97°F in Alameda County, provide afternoon shade for Tomatillo and water deeply in the morning.
Common pests for Tomatillo in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
Alameda County receives only 16" of rain annually. Tomatillo needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Tomatillo in Other Locations
Frequently Asked Questions
When should I plant Tomatillo in Alameda County, CA?
Alameda County is in Zone 10a with an average last frost of January 18. Plan your Tomatillo planting based on this frost date — see the calendar above for exact timing.
What planting zone is Alameda County, CA?
Alameda County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.
Your Alameda County Garden Planner — Free
A 24-page printable planner built for Alameda County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.