When to Plant Onion in Trinity 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.
Trinity County, California is in USDA Zone 7b. The average last spring frost is April 19 and the first fall frost is October 25, giving you a growing season of approximately 189 days.
At an elevation of 61 feet, Trinity County receives approximately 30.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 79°F, so choose short-season varieties of Onion to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Onion will need more frequent watering and organic matter to retain nutrients.
Trinity County Soil Profile
Soil Type
Sandy Loam
Soil pH
6-7.1
Drainage
Well Drained
Onion Planting Timeline — Trinity County, CA
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 15 | Mar 15 – Mar 29 |
| Transplant Outdoors | April 19 | Apr 19 – May 3 |
| Direct Sow | April 5 | Apr 5 – Apr 26 |
| Fall Sowing | August 16 | Aug 16 – Aug 30 |
| Harvest | July 19 | Jul 19 – Sep 6 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| 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 7b
Growing Season
189 days
Growing Tips for Trinity 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 Trinity County, CA?
Trinity County is in Zone 7b with an average last frost of April 19. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Trinity County, CA?
Trinity County, California is in USDA Hardiness Zone 7b. The average last spring frost is April 19 and first fall frost is October 25.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Trinity County gardeners in Zone 7b organize planting dates, track what's growing, and never miss a planting window.
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