All US plant patents

Every US plant patent granted since 1931 — 33,396 of them, of which 32,389 record a cultivar name and 14,642 have already expired. Each has its own page with the official expiration date, the record it came from, and the claim.

When they come off patent

Counted by the official expiration date on each patent, not by filing date plus twenty years.

A patent expiring frees the plant, not the name. Trademarks renew indefinitely, so check the mark separately before selling under a brand name.