When to plant Fennel (Bulb/Florence)
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 Fennel (Bulb/Florence) 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 | Not available | Not available | Not available | – |
| 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 semi hardy crop. In climates like this one, hardy and semi-hardy crops typically go in during the cooler months (fall through late winter), not on a frost-relative schedule.
Bulb fennel carries no frost-week figure on this page, and the semi-hardy classification shown for it is this page's own inference, not a tier NC State Extension assigns directly. NC State's Central North Carolina Planting Calendar (AG-756-01), the only source held for this crop after several other land-grant fennel pages returned dead links, gives calendar planting dates, February 15 through August 15, and a 60-to-90-day maturity range, but no hardiness tier and no weeks-before-frost rule.
Fennel is widely treated as a cool-season crop able to take light frost, the reasoning behind the semi-hardy label here, but that reasoning is flagged as lower-confidence than every other crop on this page, since it rests on general horticultural pattern rather than a number NC State itself states.
With only calendar dates and no frost offset to work with, a cold-winter climate should treat NC State's February 15 start as the earliest realistic end of that window and expect it to run later locally; a mild-winter climate has more room across NC State's full February-through-August span to plant more than once.
Bulb fennel is a direct-seed or transplant crop depending on the planting date; nurseries typically carry it as seed for the early planting and sometimes as transplants closer to the calendar's later start dates.
Frost hardiness
Semi-hardy. Tolerates light frost. Best planted close to the last frost date.
Days to maturity
60–90
Sourcing notes
Single-sourced despite genuine effort to find a second land-grant citation (Clemson, Penn State, Oregon State, and University of Minnesota fennel pages all returned 404/403 on direct fetch, and the WebSearch tool's session budget was exhausted before a working URL could be located). NCSU gives only calendar dates (Feb15-Aug15) and DTM (60-90 days), not a hardiness tier or a weeks-before-frost rule. semi_hardy is an inferred classification (fennel is widely treated as a hardy-ish cool-season crop able to tolerate light frost) rather than a number taken directly from NCSU - flagged as lower-confidence than every other row in this file. Direct-sow/transplant and fall-weeks fields left blank since no source gives them.
Related crops
Growing zones for this crop
Nurseries near these locations
Sources
- NC State Extension, Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs (AG-756-01) (accessed 2026-08-04)