Salsify (cool-season root vegetable) is classed hardy in the cited extension guidance. The timing rules below are relative to your local freeze dates — enter a location to turn them into calendar dates.
The rules this site applies
Method
Frost-relative window
Rule & reconciliation
Fall planting
100–86 days before the median first fall freeze
University of Arkansas Cooperative Extension fact sheet FSA6094 says to "Plant the seed in deep, well-prepared fertile soil in late spring or summer (about 100 days before freezing weather)," and the parenthetical — the only frost-anchored part of the instruction — encodes as a 14-day sowing span opening 100 days before the first freeze; no other extension source with a frost-relative salsify rule was found, so nothing required reconciling.
No direct-sow outdoors window: The University of Arkansas fact sheet gives salsify's spring timing only as a season ("seed late winter or spring"), not as an offset from the last spring freeze, so no spring window is computed here.
Variety assumption: Assumes true salsify (Tragopogon porrifolius) such as Mammoth Sandwich Island at about 120 days; note the Arkansas fact sheet heads its section "Salsify – Tragopogon porrifolius or Scorzonera hispanica" and lists a black-rooted scorzonera cultivar alongside it, so this entry deliberately covers only Tragopogon and black salsify is left as a separate plant.