When to Plant Echinacea in King County, WA
Echinacea (purple coneflower) is a native prairie perennial valued for its immune-supporting properties and beautiful daisy-like flowers that attract pollinators.
King County, Washington is in USDA Zone 8b. The average last spring frost is April 7 and the first fall frost is October 30, giving you a growing season of approximately 206 days.
At an elevation of 258 feet, King County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Echinacea during the growing season.
King County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.4
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
Echinacea Planting Timeline — King County, WA
Echinacea Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Harvest | August 18 | Aug 18 – Nov 24 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | — |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Low — drought tolerant
Days to Maturity
120–180 days
Soil pH
6 – 7
USDA Zone
Zone 8b
Growing Season
206 days
Growing Tips for King County
Start seeds indoors 8-10 weeks before last frost or direct sow in fall for spring germination. Seeds need cold stratification. Deadhead to prolong blooming or leave seed heads for birds.
Companion Planting
Good Companions
Level Up Your Garden
Echinacea in Other Locations
Frequently Asked Questions
When should I plant Echinacea in King County, WA?
King County is in Zone 8b with an average last frost of April 7. Plan your Echinacea planting based on this frost date — see the calendar above for exact timing.
What planting zone is King County, WA?
King County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 7 and first fall frost is October 30.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help King County gardeners in Zone 8b organize planting dates, track what's growing, and never miss a planting window.
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