When to plant rutabaga in Billings, Montana
June 23 – July 7
Fall planting · typical Billings yearClimate basis: NOAA station Billings Wtp, MT (USC00240802), 13 mi (21 km) from downtown Billings (ZCTA 59101 centroid), elevation 3097 ft, on the 1991–2020 climate normals. Plant rutabaga for fall from approximately the dates above, anchored to the median first fall 32°F freeze (October 1). One year in ten still freezes after May 24.
The Billings year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to May 24
Every method, with its sources
Fall planting
Jun 23 – Jul 7University of Illinois Extension says "For fall harvest, plant rutabagas about 100 days before the first frost," a point rule that opens a 14-day sowing span 100 days ahead of the first fall freeze; UGA Circular 942 agrees the crop is frost-anchored ("2 ½ to three months before a heavy frost") but ties itself to a heavy frost rather than the first 32°F freeze that this engine uses as its anchor, so the Illinois wording — which names the first frost directly — was the one encoded. Anchored to the median first fall freeze (Oct 1). University of Illinois Extension · University of Georgia Extension
Start seeds indoors
Not calculatedThe cited extension guides do not time an indoor seed-starting window for this crop.
Transplant outdoors
Not calculatedThe cited extension guides do not time an outdoor transplanting window for this crop.
Direct-sow outdoors
Not calculatedIllinois Extension states a frost-relative rule only for the fall crop ("plant rutabagas about 100 days before the first frost"); its spring sentence covers turnips rather than rutabagas, so no spring window is computed here.
Variety assumption: Assumes a standard 90-day variety such as American Purple Top or Laurentian grown as a fall crop; Illinois Extension notes rutabagas need about four weeks longer than turnips, which is why only a fall window is encoded.
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 Illinois Extension: Turnip | Home Vegetable Gardening (accessed 2026-07-25)"For fall harvest, plant rutabagas about 100 days before the first frost, and plant turnips about 3 to 4 weeks later."
- University of Georgia Extension: Growing Rutabagas in the Home Garden (Circular 942), Terry Kelley and Robert Westerfield (accessed 2026-07-25)"Rutabagas should be seeded 2 ½ to three months before a heavy frost."