When to plant bulb fennel in Charlotte, North Carolina

March 30 – April 13

Direct-sow outdoors · typical Charlotte year

Climate basis: NOAA station Charlotte Douglas AP, NC (USW00013881), 6 mi (10 km) from downtown Charlotte (ZCTA 28202 centroid), elevation 728 ft, on the 1991–2020 climate normals. Direct-sow bulb fennel from approximately the dates above, anchored to the median last spring 32°F freeze (March 30). One year in ten still freezes after April 14.

Last spring freezeMarch 301-in-10 after Apr 14

First fall freezeNovember 31-in-10 before Oct 22

Frost-free season≈ 221 daysmedian at 32°F

Hard freeze, 28°Mar 17 – Nov 14kills even hardy greens

USDA zone8a10 to 15°F winter low — not frost timing

The Charlotte year

Start seeds indoorsFeb 16 – Mar 2

Direct-sow outdoorsMar 30 – Apr 13

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 14

Bulb Fennel in Charlotte · freeze context from Charlotte Douglas AP, NC, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 16 – Mar 2

Wisconsin Horticulture (University of Wisconsin-Madison Division of Extension) states "Plants can be started indoors 4 to 6 weeks before the last spring frost," giving a sowing span from six to four weeks ahead of the last frost; no competing extension figure was found, so it is encoded as printed. Anchored to the median last spring freeze (Mar 30). University of Wisconsin-Madison Division of Extension (Wisconsin Horticulture)

Direct-sow outdoors

Mar 30 – Apr 13

The same Wisconsin Horticulture article says to "Sow seeds about ¼ inch deep after the last frost in spring, or in mid-summer for a fall crop of Florence fennel," and the first clause is a point rule at the last frost that opens a 14-day sowing span; the article's mid-summer alternative is a fixed-calendar rule with no frost relation and so was not encoded. Anchored to the median last spring freeze (Mar 30). University of Wisconsin-Madison Division of Extension (Wisconsin Horticulture)

Variety assumption: Assumes a bulbing Florence type (finocchio) rather than the non-bulbing herb fennel grown for leaf and seed; the cited article covers Foeniculum vulgare generally but names Florence fennel explicitly in its sowing sentence.

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (1)

University of Wisconsin-Madison Division of Extension (Wisconsin Horticulture): Fennel, Foeniculum vulgare, Susan Mahr (accessed 2026-07-25)
"Plants can be started indoors 4 to 6 weeks before the last spring frost."

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