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If the roses are still completely dormant, plant them now. If they have leafed out, store them until the temperatures have warmed a bit. If you are just buying roses, find some that are own-rooted (not grafted) as the grafted roses have a hard time surviving in Zone 7. In a couple years, you will only have the root stock - pretty but if you wanted all red roses, you would have planted all red roses.
Own-rooted roses can die to the ground and come back up from the roots.
If you did buy grafted roses, plan to put a mound of compost on them every winter, the deeper the better.
Don't prune until after the roses leaf out each spring. That way, you will know what survived the winter; sometimes just cutting out the dead stuff is all that is needed.
Daisy