When to Plant Sunflower in Harris County, TX
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.
Harris County, Texas is in USDA Zone 9a. The average last spring frost is February 14 and the first fall frost is December 4, giving you a growing season of approximately 293 days.
At an elevation of 390 feet, Harris County receives approximately 67.7 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 102°F, so Sunflower may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Sunflower will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.
Harris County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.3-6.5
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
Sunflower Planting Timeline — Harris County, TX
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 3 | Jan 3 – Jan 17 |
| Transplant Outdoors | February 21 | Feb 21 – Mar 7 |
| Direct Sow | February 14 | Feb 14 – Mar 7 |
| Harvest | May 2 | May 2 – Jun 20 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Transplant Outdoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | — |
| 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
6 – 7.5
USDA Zone
Zone 9a
Growing Season
293 days
Growing Tips for Harris 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
Level Up Your Garden
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Harris County, TX?
Harris County is in Zone 9a with an average last frost of February 14. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harris County, TX?
Harris County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 14 and first fall frost is December 4.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Harris County gardeners in Zone 9a 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.