Daniel Gill, Merrill, Thomas A. | 4/19/2005 10:28:56 PM
By Dan Gill
LSU AgCenter Horticulturist
It’s hard to imagine a more delightful perennial than the daylily. Available in an amazing variety of colors, shapes and sizes, there are daylilies to fit virtually every taste and garden situation.
Daylilies are coming into bloom now, and gardeners would be hard pressed to find a plant that provides so many colorful flowers for so little effort.
Although it’s not a true lily, the daylily is a member of the lily family. Its botanical name, Hemerocallis, is derived from two Greek words meaning "day" and "beauty" and refers to the fact that daylily flowers last only a day before they fade. This might seem to be a major flaw, but these plants produce so many flowers over an extended period, you hardly notice that each one lasts such a brief time.
Breeders have developed the daylily into an incredibly diverse plant. With careful cultivar selection, you can have daylilies in bloom from late spring to early fall. The heights of various cultivars range from 8 inches to several feet (including the flower scapes), and the diameters of the blooms may vary from 2½ inches to as large as 8-9 inches. And the flowers come in a multitude of color combinations including yellow, orange, rose, burgundy, purple, pink, cream, lavender, red and many others.
Daylilies have three types of foliage habit. Dormant daylilies lose their foliage completely during the winter. Then new foliage appears in the spring. Evergreen daylilies retain their foliage throughout the year. And semi-evergreen daylilies’ foliage dies part way back in the winter but begins to grow again after a brief rest. Gardeners in our area should grow evergreen or semi-evergreen types.
Most daylilies bloom best in full sun. They will tolerate partial shade but require at least 6 hours of direct sun each day for best results. Light yellow varieties, many shades of pink and other delicate pastels need full sun to bring out the colorings, while deeper colors may benefit from shade in the hottest part of the day.
Any good garden soil is fine for growing daylilies. They thrive in a variety of soils, ranging from light sandy types to heavy clays. To get any soil in good physical condition, dig it deeply and work in generous amounts of organic matter such as well-rotted manure, compost or peat moss. This organic matter makes the soil easier to work and helps retain soil moisture. It also acts as a storehouse for plant nutrients. For best performance, plant daylilies in well-drained soil.
Early spring or late fall are the most desirable planting times, but well-established plants grown in containers and bought locally can be planted virtually anytime. Space daylilies 18 to 24 inches apart. Some varieties multiply fast, and the clumps will become crowded if planted too close to each other.
Although daylilies generally don’t need to be pampered, an adequate supply of water will ensure peak performance, especially the first year after planting. During the summer, plantings should be watered once or twice a week when weather is hot and dry. Water deeply, soaking the soil to a depth of 6-8 inches, and water each week when there is not at least 1 inch of rainfall. A 2-inch mulch of leaves or pine straw will help conserve moisture and reduce weed problems.
A single application of a complete fertilizer in March generally is adequate, although a second application could be made in June. Use any general-purpose fertilizer. A final application can be made in early fall because a new surge of growth occurs at that time on many cultivars. Keep the fertilizer off the foliage, and water it into the soil after applying.
Aphids are the most serious insect pest of daylilies. They are most common in the late winter and early spring and cause the leaves and flowers to be unhealthy and deformed. Treatment with acephate is effective if the infestation is severe enough to warrant it.
You also need to be aware of a new fungus disease called daylily rust that is causing concern. Daylily rust was first reported in the southeastern United States in 2000 and has spread rapidly to many states, including Louisiana. The disease causes the foliage to yellow and brown.
If you turn over a leaf infected with daylily rust, you will see orange raised spots on the back of the leaf. The rusty orange spores will rub off on your finger. Susceptibility of daylily cultivars to this disease varies. Some are very susceptible, and others seem fairly resistant. Gardeners have the choice of eliminating the very susceptible cultivars, which show the worst symptoms, and retaining those that don’t seem to be bothered as much by the disease.
Should a gardener decide to treat the disease, an infected plant should be cut down to within an inch of the ground. Then that plant and all the plants around it should be sprayed regularly with a fungicide. Recommended fungicides include mancozeb (Dithane, Fore), chlorothalonil (Daconil), azoxystrobin (Heritage), propiconizol (Banner Maxx) and triadimefon. Applications may need to be repeated as often as every seven days to 14 days, and, as always, follow product label instructions carefully.
It is likely that the best solution to this problem will be to use existing cultivars and develop new ones that are resistant to the disease. More information on daylily rust can be found on the Internet at www.daylilies.org/ahs_dictionary/daylily_rust.html.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.