The three varieties grown in 2019 are of the same species,Persicaria Tinctoria a member of the knotweed family. Before you let a gasp of horror as many associate knotweed as an invasive plant. Please know the conditions in which indigo is harvested reduces the likelihood of “Self seeding” (as described in this previous blog *Here) and unless seed is required. Winters frost will also knock out the spread of any remaining seed and future plant growth. I have yet to see plants withstand a British winter even during our milder weather in the Bailiwick of Guernsey, Channel Islands, UK.