@CarolineScott - There are several type of Dietes in the data base here. This is the one I am growing.
Butterfly Iris (Dietes grandiflora)
I don't remember how many I planted - likely 6 cells. The pot I have them in has 3 or 4 plants and I will likely up-size the pot this year.
They are tender in my zone as they are from S. Africa. During the Summer, I place them outside in full sun. I bring them in mid October and have kept them in my back bedroom now for 2 winters where they get West window sun. I also have Dierama in there with them among other tropicals and tenders.