When to Plant Echinacea in Contra Costa County, CA
Echinacea (purple coneflower) is a native prairie perennial valued for its immune-supporting properties and beautiful daisy-like flowers that attract pollinators.
Contra Costa County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 29, giving you a growing season of approximately 276 days.
At an elevation of 88 feet, Contra Costa County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Echinacea during the growing season. With low rainfall, drip irrigation is essential for growing Echinacea successfully. Mulch heavily to conserve soil moisture.
Contra Costa County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
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
Echinacea Planting Timeline — Contra Costa County, CA
Echinacea Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 5 | Mar 5 – Mar 19 |
| Harvest | July 9 | Jul 9 – Oct 15 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Transplant Outdoors |
| April | — |
| May | — |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| 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 9b
Growing Season
276 days
Growing Tips for Contra Costa 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 Contra Costa County, CA?
Contra Costa County is in Zone 9b with an average last frost of February 26. Plan your Echinacea planting based on this frost date — see the calendar above for exact timing.
What planting zone is Contra Costa County, CA?
Contra Costa County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 29.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Contra Costa County gardeners in Zone 9b organize planting dates, track what's growing, and never miss a planting window.
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