Mona, I use plastic kitty litter bins as pots. They are huge and deep, and the bigger ones, I stick a piece of old plywood down the middle, and can plant two daylilies in it, one on each side. I drill a couple of holes in the bottom for drainage, and I too like to pop one on top of the other when necessary.
You will LOVE Pandora's Treasure.
Michelle, your DL look great, nice job! ~Jan