When to plant celery in Knoxville, Tennessee
April 11 – April 25
Transplant outdoors · typical Knoxville yearClimate 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 celery 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.
The Knoxville year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Apr 29
Every method, with its sources
Start seeds indoors
Jan 17 – Jan 31Sow 10–12 weeks before the set-out window opens (UNH: time from seed to transplant 10–12 weeks). Anchored to the median last spring freeze (Apr 11). University of New Hampshire Extension
Transplant outdoors
Apr 11 – Apr 25UNH: set out after the last frost. Purdue's semi-hardy class allows 2–4 weeks before; the later UNH rule is used (celery is easily vernalized by cold spells). Anchored to the median last spring freeze (Apr 11). University of New Hampshire Extension · Purdue University Extension
Variety assumption: A long, steady season (about 100–120 days from transplant; Penn State lists 120).
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.
Crop rule sources (2)
- University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
- Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.