When to Plant Cauliflower in Riverside County, CA
Cauliflower is a cool-season brassica that produces dense white, purple, or green heads called curds. It is more finicky than broccoli but rewards with a mild, nutty flavor.
Riverside County, California is in USDA Zone 9b. The average last spring frost is February 24 and the first fall frost is December 4, giving you a growing season of approximately 283 days.
At an elevation of 1,206 feet, Riverside County receives approximately 15.5 inches of rainfall annually with predominantly loam soil. Summer highs average 102°F, so Cauliflower may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Cauliflower successfully. Mulch heavily to conserve soil moisture.
Riverside County Soil Profile
Soil Type
Loam
Soil pH
6.2-7.8
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 10/10 — consider drought-tolerant varieties and mulching
Cauliflower Planting Timeline — Riverside County, CA
Cauliflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 27 | Jan 27 – Feb 10 |
| Transplant Outdoors | February 24 | Feb 24 – Mar 10 |
| Direct Sow | February 3 | Feb 3 – Feb 24 |
| Fall Sowing | October 9 | Oct 9 – Oct 23 |
| Harvest | April 21 | Apr 21 – Jun 23 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
High — keep soil consistently moist
Days to Maturity
55–100 days
Soil pH
6 – 7
USDA Zone
Zone 9b
Growing Season
283 days
Growing Tips for Riverside County
Start seeds indoors 6 weeks before transplanting. Blanch white varieties by tying outer leaves over the head. Provide consistent moisture and avoid temperature extremes.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Cauliflower in Other Locations
Frequently Asked Questions
When should I plant Cauliflower in Riverside County, CA?
Riverside County is in Zone 9b with an average last frost of February 24. Plan your Cauliflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Riverside County, CA?
Riverside County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 24 and first fall frost is December 4.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Riverside County gardeners in Zone 9b organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.