.That would be what I would do. Plant them come spring as soon as the soil it able to be worked.
I don't know how you feel about plant catalogs, but the Dutch Gardens 2011 has oodles of Lilies, Asiatic, oriental, trumpets, the orienpets. just to name a few. They say zones 4. van Bourgondien has lilies also. Go to your garden centers and nurseries and see what they recommend or sell.
I can't imagine, any more, what it would be like to not have iris, lily, peonies etc. on a home landscape. They are all so colorful, fragrant and nice looking plants. When we moved to this property 6 years ago almost 7 now there was not a single flower to be found. The former owner said they didn't DO flowers Since we moved in I have put in 27 garden beds and still planning more.
Good luck hope you find some that will be what you need them to be.
Cherie
