When to plant celeriac in Knoxville, Tennessee

April 11 – April 25

Transplant outdoors · typical Knoxville year

Climate basis: NOAA station Knoxville Exp Stn, TN (USC00404946), 5 mi (8 km) from downtown Knoxville (ZCTA 37902 centroid), elevation 830 ft, on the 1991–2020 climate normals. Transplant celeriac outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 11). One year in ten still freezes after April 29.

Last spring freezeApril 111-in-10 after Apr 29

First fall freezeOctober 281-in-10 before Oct 13

Frost-free season≈ 198 daysmedian at 32°F

Hard freeze, 28°Mar 31 – Nov 6kills even hardy greens

USDA zone7b5 to 10°F winter low — not frost timing

The Knoxville year

Start seeds indoorsJan 31 – Feb 14

Transplant outdoorsApr 11 – Apr 25

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 29

Celeriac in Knoxville · freeze context from Knoxville Exp Stn, TN, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Jan 31 – Feb 14

The UC Master Gardener Program of Sonoma County (University of California Cooperative Extension) says to "Sow seed indoors as early as 10 weeks before the average last frost date in spring," so the sowing span opens ten weeks before the last frost and runs two weeks; no competing extension figure was found, so this stands without reconciliation. Anchored to the median last spring freeze (Apr 11). University of California Cooperative Extension, UC Master Gardener Program of Sonoma County

Transplant outdoors

Apr 11 – Apr 25

The same UC Master Gardener page states plants "can go into the garden 10-12 in. apart on the average date of last frost," a point rule that opens a 14-day transplanting span at the last frost date; the page's alternative air- and soil-temperature condition is not frost-anchored and was therefore not encoded. Anchored to the median last spring freeze (Apr 11). University of California Cooperative Extension, UC Master Gardener Program of Sonoma County

Variety assumption: Assumes a standard 100-to-120-day celeriac variety grown from transplants; germination is slow, so the long indoor lead time is part of the published rule rather than an added buffer.

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 California Cooperative Extension, UC Master Gardener Program of Sonoma County: Celeriac (accessed 2026-07-25)
"Sow seed indoors as early as 10 weeks before the average last frost date in spring."

Keep exploring

This crop, other cities

Related crops in Knoxville

Local overview