When to plant Sunflower
Computed from land-grant Extension planting-window rules (cited below), localized to real ZIP-level median frost dates, not a single national guess. These are national-generic rules by hardiness class; individual state Extension offices layer their own regional adjustment on top (earlier in the Deep South, later in the Upper Midwest). Enter your ZIP for your own dates, or read the four representative locations below.
Planting windows and crop timing here are computed from USDA/NOAA climate data and the university extension sources cited below, not a site visit or soil test. Treat this as a starting point: local conditions vary, and a local nursery or extension office can advise on your exact site. See our full Disclaimer.
Representative timing, by climate band
When to plant Sunflower in four US climates
Each column is the most nursery-dense location in our directory within that USDA zone band, computed from that location's own real median frost dates, not a made-up example.
| Stage |
Zones 1-5 (cold winters)
Fort Plain, NY |
Zones 6-7 (temperate)
McMinnville, TN |
Zones 8-9 (warm)
Apopka, FL |
Zones 10-13 (hot, frost rare or absent)
Loxahatchee, FL |
|---|---|---|---|---|
| Start seed indoors | Not available | Not available | Not available | – |
| Direct-sow outside | May 6–May 20 | Apr 7–Apr 21 | Feb 24–Mar 10 | – |
| Transplant outside | Not available | Not available | Not available | – |
| Fall planting | Not available | Not available | Not available | – |
| Expected harvest | Not available | Not available | Not available | – |
Zones 10-13 (hot, frost rare or absent) (Loxahatchee, FL): Frost is rare here (about 359 frost-free days a year); most years see little or no hard freeze. This is a tender crop. In climates like this one, tender and very-tender crops typically go in before the hottest months arrive, not on a frost-relative schedule.
Sunflower is a tender annual. Clemson Cooperative Extension's Growing Annuals factsheet (HGIC 1152) and University of Minnesota Extension both say to direct-seed only after all danger of frost has passed. Clemson adds a soil-temperature floor of 50°F for that direct sowing.
Iowa State University Extension's Growing Sunflowers and Their Varieties gives 70 to 100 days from planting to seed-head, or harvest, maturity, but that's a seed-maturity count, not a first-bloom date, so it isn't used as this page's days-to-maturity figure; no source gives an explicit first-bloom day count. Iowa State also notes seedlings tolerate mild frost, which is why the direct-sow window here runs zero to two weeks after your last frost rather than strictly at the frost date.
Sunflower is grown from seed almost universally; it's not a crop nurseries sell as started transplants.
Frost hardiness
Tender. Damaged or killed by frost. Plant after the last frost date.
Minimum soil temperature
50°F
For direct sowing/germination, where an Extension source stated it.
Sourcing notes
Tender annual per Clemson Growing Annuals (HGIC 1152) and UMN Extension ("Direct seed sunflowers after all danger of frost has passed"). Clemson: direct sow once soil warmed above 50F. ISU (Growing Sunflowers and Their Varieties) gives 70-100 days from planting to seed-head/harvest maturity -- that is seed maturity, not first bloom, so it was NOT placed in days_to_maturity (schema wants days-to-first-bloom); no extension source gave an explicit first-bloom day count. Seedlings tolerate mild frost per ISU, so direct-sow window is bracketed 0-2 weeks after last frost rather than strictly "0."
Related crops
Growing zones for this crop
Nurseries near these locations
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Sources
- Clemson Cooperative Extension Home & Garden Information Center, Growing Annuals (HGIC 1152) (accessed 2026-08-04)
- Clemson Cooperative Extension Home & Garden Information Center, Let's Grow Sunflowers (accessed 2026-08-04)
- Iowa State University Extension and Outreach (Yard and Garden), Growing Sunflowers and Their Varieties (accessed 2026-08-04)
- University of Minnesota Extension, Sunflowers (accessed 2026-08-04)