When to plant lettuce in Sioux Falls, South Dakota
April 3 – April 17
Transplant outdoors · typical Sioux Falls yearClimate basis: NOAA station Sioux Falls, SD (USW00014944), 2 mi (3 km) from downtown Sioux Falls (ZCTA 57104 centroid), elevation 1430 ft, on the 1991–2020 climate normals. Transplant lettuce outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 1). One year in ten still freezes after May 14.
The Sioux Falls year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to May 14
Every method, with its sources
Start seeds indoors
Feb 27 – Mar 13Sow 4–5 weeks before the set-out window opens (UNH 4–5 weeks; Missouri G6570 lists 6–8 weeks for head lettuce). Anchored to the median last spring freeze (May 1). University of New Hampshire Extension · University of Missouri Extension
Transplant outdoors
Apr 3 – Apr 17UNH: safe to set out 3–4 weeks before the last frost. Anchored to the median last spring freeze (May 1). University of New Hampshire Extension
Direct-sow outdoors
Apr 10 – Apr 24Purdue: semi-hardy — 2–4 weeks before the last frost; Penn State's earliest sowing Apr 10 (−21 days) is the later start and is used. Anchored to the median last spring freeze (May 1). Penn State Extension (York County Master Gardeners) · Purdue University Extension
Fall planting
Aug 11 – Sep 8Purdue Table 2: plant fall lettuce at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 6). Purdue University Extension
Variety assumption: Assumes leaf lettuce (about 45–55 days; head types run longer).
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 (4)
- 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.
- University of Missouri Extension: Starting Plants Indoors from Seeds (G6570) (accessed 2026-07-24)Weeks needed to grow vegetable transplants indoors (Table 2).
- Penn State Extension (York County Master Gardeners): Vegetable Seed Planting Guide (accessed 2026-07-24)Earliest/latest sowing dates for a May 1 last-frost / Oct 1 first-frost baseline; offsets derived by date difference from May 1. Also days-to-maturity figures.
- 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.