Fall Care of Daylilies

One of the joys of the perennial garden is that its residents reappear in the spring without replanting. Some perennials have needs to keep them healthy and pest-free over the winter. Daylilies (Hemerocallis spp.), on the other hand, are among those plants that require only careful sanitation and a light mulch to carry them through the winter. Better still, fall is a prime time to divide daylilies to increase your collection and share with gardening friends.

Daylilies fill gardens from U.S. Department of Agriculture plant hardiness zone 3 through 9, although not all plants are hardy throughout the entire range. Modern hybrids have been chosen for their ability to re-bloom and are called "remontant" daylilies; "Stella D'Oro" (Hemerocallis "Stella D'Oro") is an example. Other modern hybrids are evergreen or semi-evergreen that undergo only a short dormant period in warmer USDA zones 6 through 9. Year-round deadheading and removal of dead leaves are especially important with remontants and evergreens.

Although Southern daylily growers might treat their plants to an August feeding of 10-10-10 garden fertilizer, in those places where freezing temperatures last for weeks or months, fall feeding encourages growth, which can damage the crown when tender new foliage freezes. Plants from USDA zones 6 or 7 northward should not be fertilized after early summer.

Daylilies need two things to flower heavily -- sunshine and water. Ensure that plants get their weekly inch of water throughout the summer. Once flowering ends, the need for water decreases, but plants still need moisture during dry spells. Daylilies have relatively deep roots, so water them until moisture reaches a depth of 8 inches. Gradually withhold water as the weather cools and plants begin to go dormant.

Deadheading spent blooms and their tall branches, called scapes, encourages re-bloom in many daylilies and improves the appearance of all plants. Tug dead leaves out of the crown to make room for the second flush of growth that occurs in late summer. Cutting daylilies back after the first freeze cues them to begin dormancy to deny critters a winter home. Trim fans to 3 or 4 inches -- these remnants will fall away next spring. Whenever you deadhead or cut back foliage, sanitize hand-shear blades by wiping them with a half-and-half solution of rubbing alcohol and water.

Daylilies can be divided in spring or fall, so as long as you're cutting them back, take the opportunity to pull clumps apart with a garden fork and replant divisions containing three to five crowns for blooms next year. Dig holes twice as wide as the plant and spread roots so the crown sits less than an inch below the soil's surface.

Daylilies are rugged plants and don't require mulching in northern gardens unless they're recent transplants. A 2- to 3-inch layer of pine straw or bark, however, will keep the soil in southern gardens from sudden daytime warming that can interrupt daylilies' need for chilling during dormancy. Whether you mulch or not, don't cover the area around the crown.