When to Plant Onion in Tehama County, CA
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Tehama County, California is in USDA Zone 8b. 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 78 feet, Tehama County receives approximately 44 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Onion to ensure they mature before fall.
Tehama County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.6
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.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Onion Planting Timeline — Tehama County, CA
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 30 | Jan 30 – Feb 13 |
| Transplant Outdoors | March 6 | Mar 6 – Mar 20 |
| Direct Sow | February 20 | Feb 20 – Mar 13 |
| Fall Sowing | September 19 | Sep 19 – Oct 3 |
| Harvest | June 5 | Jun 5 – Jul 24 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | — |
| June | Harvest |
| July | Harvest |
| August | — |
| September | Fall Sowing |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
USDA Zone
Zone 8b
Growing Season
267 days
Growing Tips for Tehama County
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Tehama County, CA?
Tehama County is in Zone 8b with an average last frost of March 6. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Tehama County, CA?
Tehama County, California is in USDA Hardiness Zone 8b. The average last spring frost is March 6 and first fall frost is November 28.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Tehama County gardeners in Zone 8b organize planting dates, track what's growing, and never miss a planting window.
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