When to Plant Sunflower in Marlboro County, SC
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.
Marlboro County, South Carolina is in USDA Zone 8a. The average last spring frost is March 23 and the first fall frost is November 6, giving you a growing season of approximately 228 days.
At an elevation of 132 feet, Marlboro County receives approximately 52.7 inches of rainfall annually with predominantly clay loam soil. Summer highs average 91°F, providing good warmth for Sunflower during the growing season. Clay soil retains moisture well for Sunflower, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.
Marlboro County Soil Profile
Soil Type
Clay Loam
Soil pH
5.7-6.5
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 — Marlboro County, SC
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 2 | Feb 2 – Feb 16 |
| Transplant Outdoors | April 6 | Apr 6 – Apr 20 |
| Direct Sow | March 30 | Mar 30 – Apr 20 |
| Harvest | June 15 | Jun 15 – Aug 3 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| 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 8a
Growing Season
228 days
Growing Tips for Marlboro 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 Marlboro County, SC?
Marlboro County is in Zone 8a 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 Marlboro County, SC?
Marlboro County, South Carolina is in USDA Hardiness Zone 8a. The average last spring frost is March 23 and first fall frost is November 6.
Plan Your Garden with Confidence
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