No, they are definitely not. I have only been purchasing daylilies for about 3 years now and have purchased them from many sources - ebay to Daylily Auction to directly from sellers or hybridizers and many have died from crown rot or just kindof died away and these were mainly Evergreens with a couple of SE or D thrown in. I have tried three times with Free Wheelin' and finally purchased my last plant from a norther grower. It did bloom, but has not been through a winter yet, and it is an Evergreen. I have heard from some other people that is tender in zone 5. There are many blogs around that speak about hardiness or tenderness of certain plants also. Sometimes I check and sometimes I just buy them if I just have to have them. Free Wheelin' was the very first daylily I purchased and don't want to give up, but if it dies this winter, I will give up on it.
I have purchased many daylilies from people in FL and GA several times and most of the daylilies I have purchased from them are doing great. Some hybridizers will tell you if they think a daylily won't make it in your zone. For example, Dan Hansen of Ladybug Daylilies sends his daylilies to someone in Ohio to check on their hardiness and has a section on his website for his tested Zone 5 hardy daylilies. He will not sell you a daylily that he knows won't do well in your zone. I have been to his garden and I can attest to this personally. Also, there is a link on Cottage in the Meadows' website that shows the Evergreen daylilies that are zone 5 hardy as either tested by them or by other growers in zone 5. I am also participating with their list. You could do the same...
https://cottageinthemeadow.pla...