I've often grown daylilies indoors during the winter, usually new ones received too late in the season to plant in this climate, or to watch for spring sickness. They go on a sunny windowsill facing south-east with no supplemental lighting and some do flower if they are of flowering size. Winters here are very cold and the room can be cool especially close to the window. If they are brought in after the leaves have died back most sprout and start to grow within a week or so of coming indoors (whatever their registered "foliage habit").
