Day Lilies are undemanding members of the lily family whose genus name , Hemerocallis, is Greek for "beauty for a day." The only attention these hardy perennials need in winter is a blanket of mulch. After the first hard frost, cover the ground with a loose, 3 to 5 inch layer of evergreen boughs, bark chips, straw, or leaves.
Division is needed only in established clumps that have become too large, or those whose flowers have become sparse or small. This may be several years away. Either with a pitch fork or shovel dig each clump up and divide the clump with a sharp object such as a large knife. You can also separate the clump with two pitch forks. Divide into individual plants and replant.
Make sure you fertilize with a high phosphorus fertilizer for best flower product. Usually Day Lilies are pest and disease free.