When to Plant Onion in Stevens County, WA
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.
Stevens County, Washington is in USDA Zone 5b. The average last spring frost is May 10 and the first fall frost is September 24, giving you a growing season of approximately 137 days.
At an elevation of 1,751 feet, Stevens County receives approximately 24.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Onion to ensure they mature before fall.
Stevens County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.3
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
Onion Planting Timeline — Stevens County, WA
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 5 | Apr 5 – Apr 19 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Fall Sowing | July 16 | Jul 16 – Jul 30 |
| Harvest | August 9 | Aug 9 – Sep 27 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | 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 5b
Growing Season
137 days
Growing Tips for Stevens 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 Stevens County, WA?
Stevens County is in Zone 5b with an average last frost of May 10. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Stevens County, WA?
Stevens County, Washington is in USDA Hardiness Zone 5b. The average last spring frost is May 10 and first fall frost is September 24.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Stevens County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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