When to plant winter rye in Boise, Idaho
September 12 – September 26
Fall planting · typical Boise yearClimate basis: NOAA station Boise 7 N, ID (USC00101017), 6 mi (9 km) from downtown Boise (ZCTA 83702 centroid), elevation 3885 ft, on the 1991–2020 climate normals. Plant winter rye for fall from approximately the dates above, anchored to the median first fall 32°F freeze (October 12). One year in ten still freezes after June 10.
The Boise year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Jun 10
Every method, with its sources
Fall planting
Sep 12 – Sep 26UMass Extension's cover-crop fact sheet sets the general rule at about 30 days before the first expected frost date and, in the following sentence, names winter rye as a species that may go in a little closer to that date; the stated 30-day point is taken as the window opening and expanded to the standard 14-day span, with rye's tolerance for later seeding noted rather than quantified, since "a little closer" prints no number. Anchored to the median first fall freeze (Oct 12). UMass Amherst Center for Agriculture, Food, and the Environment
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 calculatedThe cited extension guides do not time direct sowing for this crop.
Variety assumption: Assumes seeding for overwintering ground cover with most growth resumed in early spring, then turned under before the next crop.
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 (1)
- UMass Amherst Center for Agriculture, Food, and the Environment: Cover Crops — growing tips (accessed 2026-07-25)"As a general rule, cover crops should be planted about 30 days before the first expected frost date."