Daylilies seem to grow themselves. Patches of hemerocallis fulva and hemerocallis flava still bloom where early settlers and pioneers planted them in the 18th and 19th centuries. Today's fancy hybrids may not be quite as care-free as the old tawny and lemon lilies, but the daylily is still one of the hardiest, most productive perennials in the home garden. With proper placement and some simple care, it is one of the least demanding flowers we grow.
Locate daylilies where they will get from 4 to 8 hours of sun per day; more sun encourages more blooms and better color. Avoid placing dark-colored daylilies where they will get sun during the hottest part of the day, though, because it may fade their colors. Daylilies get along with other perennials, but they will spread each year and may shade smaller plants.
Prepare the soil before planting daylilies by adding well-rotted compost or manure to heavy soils. Daylilies prefer well-drained, loamy soil for their thick root systems. They make good plants for hilly areas; the soil drains well, and they return the favor by holding it in place and controlling erosion.
Space short daylilies at least a foot apart. Taller species should be planted as far apart as they will be tall to allow for the clump of plants that will grow. Set their crowns (the white area where the green leaf fan meets the roots) no more than 1 inch underground. Properly spaced daylilies seldom develop mold or virus diseases.
Water daylilies for good health; they need about 1 inch of water a week, particularly during hot and dry periods of the summer. The American Hemerocallis Society recommends fertilizing daylilies in the spring after planting with 1/4 cup of a slow-release general fertilizer (10-10-10). Daylilies that get enough water and sunlight may not need any more fertilizer, but some hybrid types will benefit from a yearly feeding.
Keep daylilies groomed to avoid insect pests that feed on decaying plants and root rot that can affect crowns that are covered by decaying material. Pull off dying leaves on the outside of fans; new leaves grow from the inside of the fan. Pinch off flowers each day as they fade, and snip off scapes (long stems on which the daylily flowers bloom) after blooms have finished if you are not going to collect seeds. Cultivate between plants and weed them regularly; grassy weeds often arrive with new plants.