When to plant sage in Boise, Idaho
May 17 – May 31
Transplant outdoors · 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. Transplant sage outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 17). 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
Start seeds indoors
Mar 22 – Apr 5Wisconsin Horticulture says to start sage indoors 6 to 8 weeks before the average date of last frost, so sowing runs 8 to 6 weeks before the last spring freeze. Anchored to the median last spring freeze (May 17). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · University of Maryland Extension
Transplant outdoors
May 17 – May 31UMD Extension names sage among herbs started indoors and planted outside after the danger of frost has passed, which coincides with Wisconsin Horticulture's direct-sow date, so the window opens at the last spring freeze. Anchored to the median last spring freeze (May 17). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · University of Maryland Extension
Direct-sow outdoors
May 17 – May 31Wisconsin Horticulture gives a point rule — plant sage seed directly in the garden on the average date of last frost — which opens a two-week sowing span beginning at that date. Anchored to the median last spring freeze (May 17). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · University of Maryland Extension
Variety assumption: Wisconsin Horticulture notes seed-grown sage may not flower the first year; culinary leaf harvest is unaffected.
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 Wisconsin-Madison Division of Extension, Wisconsin Horticulture: Sage, Salvia officinalis (accessed 2026-07-25)"To grow from seed, either plant directly in the garden on the average date of last frost or start indoors 6 to 8 weeks before then."
- University of Maryland Extension: Care of Herbs and Starting Herbs from Seed (accessed 2026-07-25)"Basil, parsley, sage, marjoram, and many other herbs can be started indoors and planted outside after the danger of frost has passed."