Potatoes (cool-season tuber) 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
Direct-sow outdoors
(plant seed pieces)
6–4 weeks before the median last spring freeze
Purdue: hardy — plant seed pieces 4–6 weeks before the last spring frost. Minnesota adds the practical caveat: plant as soon as the soil warms.
No start seeds indoors window: Potatoes are grown from seed pieces, not indoor-started seedlings.
Variety assumption: Assumes a mid-season variety (about 90–110 days from planting).
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.