When to plant endive and escarole in Boise, Idaho
May 3 – May 17
Direct-sow 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. Direct-sow endive and escarole 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
Direct-sow outdoors
May 3 – May 17Utah State University Extension lists endive seed in its semi-hardy Group B, planted "about 2 weeks before average last spring frost", so the point rule opens a 14-day span from last spring frost minus 14 to the frost date itself; Minnesota's earlier "as soon as the soil is workable" is superseded by the later, more frost-conservative USU interval. Anchored to the median last spring freeze (May 17). Utah State University Extension · University of Minnesota Extension · University of Arkansas System Division of Agriculture, Cooperative Extension Service
Fall planting
Jul 14 – Jul 28University of Minnesota Extension's direct-seeding guidance for lettuce, endive and radicchio says to "sow seed about three months before the average first fall frost date", giving a 14-day span from first fall frost minus 90 to minus 76 days. Anchored to the median first fall freeze (Oct 12). University of Minnesota Extension · University of Arkansas System Division of Agriculture, Cooperative Extension Service
Variety assumption: Endive and escarole are the curly-leaved and broad-leaved forms of one species (Cichorium endivia) and are treated as a single crop by Arkansas Extension; offsets assume the 85–98 day full-head types in its cultivar table.
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 (3)
- Utah State University Extension: Suggested Vegetable Planting Dates for Utah (accessed 2026-07-25)"Semi-Hardy (Plants a week or two after 'A' group or about 2 weeks before average last spring frost.)"
- University of Minnesota Extension: Growing lettuce, endive and radicchio in home gardens (accessed 2026-07-25)"For a fall crop, sow seed about three months before the average first fall frost date."
- University of Arkansas System Division of Agriculture, Cooperative Extension Service: Endive-Escarole (Home Gardening Series, FSA6068) (accessed 2026-07-25)"They must be grown as an early spring or fall crop."