I did the same thing a few years back when they were dirt cheap late in the season. I lost all of them. I think mine didn't have enough time to settle and establish and then I think the damp winter took care of them. You should have something growing there by now, if not, I think there are dead. Sorry.
Tabby

I am in Zone 6 in the Philly area and my May Nights are up and just begining to bloom so I think yours are goners. They are beautiful plants so try again this year with bigger plants if you can.
Joann

Hi- I have reposted this three times now!! But thank you for letting me the know the harsh reality that they are dead- I went ahead and bought a bunch of smaller plants to plant now - I read they grow fast and I hope that is true! thank you so much again!

Laura