When to Plant Sunflower in Mendocino County, CA
May in Mendocino County, California — your action list
Welcome to May in Zone 9b. These are the moves that will have the biggest impact on your growing season.
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Start sunflower under lights
Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.
Looking ahead to June
- First harvests: sunflower
Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.
Mendocino County, California is in USDA Zone 9b. The average last spring frost is March 23 and the first fall frost is November 9, giving you a growing season of approximately 231 days.
At an elevation of 180 feet, Mendocino County receives approximately 24 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Sunflower during the growing season. Sandy soil warms quickly in spring — great for early planting — but Sunflower will need more frequent watering and organic matter to retain nutrients.
Mendocino County Soil Profile
Soil Type
Sandy Loam
Soil pH
6.1-7.2
Drainage
Well Drained
Monthly Watering Guide for Sunflower
Sunflower needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sunflower Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 5.2" | 0" | ❄️ Dormant |
| Feb | — | 4.6" | 0" | ❄️ Dormant |
| Mar | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Apr | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| May | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Jun | 4.3" | 0.2" | 4.1" | 🚿 Regular watering |
| Jul | 4.3" | 0" | 4.3" | 🚿 Regular watering |
| Aug | 4.3" | 0" | 4.3" | 🚿 Regular watering |
| Sep | 4.3" | 0.2" | 4.1" | 🚿 Regular watering |
| Oct | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Nov | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Mendocino County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sunflower Planting Timeline — Mendocino County, CA
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 9 | Feb 9 – Feb 23 |
| Transplant Outdoors | March 30 | Mar 30 – Apr 13 |
| Direct Sow | March 23 | Mar 23 – Apr 13 |
| Harvest | June 8 | Jun 8 – Jul 27 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Transplant Outdoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 9b
📆 Growing Season
231 days in Mendocino County
Growing Tips for Mendocino County
Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Mendocino County, CA?
Mendocino County is in Zone 9b with an average last frost of March 23. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mendocino County, CA?
Mendocino County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 23 and first fall frost is November 9.
Your Mendocino County Garden Planner — Free
A 24-page printable planner built for Mendocino County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.