I personally buy more from Brent and Becky as they grow better than the other place. Now they will not always come back in zone 7 but I buy the cheaper ones and put them in pots to enjoy where I want color at the time they are in bloom.
I agree with Harmony and also Natasha has rotted twice on me so not going to buy that one. Since I like these for my gardens, I get the cheaper ones and enjoy the early iris bloom.
I now have about 5 Louisana Polly so trying them, if they become invasive here in OR they will not stay, as the OLDER ones I would have to thin them down monthly as they all came with bags and bags of baggage,.
D