Daylilies are popular perennials that can be grown as far north as the Canadian border. They are relatively low maintenance plants with large, brightly colored blooms. Many gardeners consider daylilies the perfect flower. They attract few pests, prosper in most climates and are generally disease-free. However, like everything that grows outdoors, disaster can strike. Bugs can infest the foliage, disease can kill the plant, and negative conditions can destroy bulbs.
The elements play a major roll in daylilies’ success. They prefer full to partial sun. When bulbs are planted or relocated in shadier areas, they tend to produce fewer and less robust blooms. Areas with poor drainage may cause damage to the roots in times of excess rain fall, which can ultimately destroy the plant, warns the Gulf Coast Daylily Society of Southeast Texas. Planting during harsh weather also may contribute to the plant’s demise. Oak Forest Technology Solutions recommends planting after the last freeze in cooler climates and after the heat of summer in warmer areas.
Daylilies typically grow well in a variety of soil types all across the United States. They do not fare as well, though, in areas with extremely sandy soil like coastal areas or deserts. Nor do daylilies perform as well in soil that is too hard. According to Oak Forest Technology Solutions, adding humus to sandy or hard soil helps daylilies having problems in harsh soil conditions.
Most daylilies are touted by nurseries as pest-free. They are relatively pest-free, but not completely exempt from infestation. Many insects like aphids, spiders, thrips and mites can wreak havoc on daylilies. Snails and slugs can cause damage as well. The Gulf Coast Daylily Society of Southeast Texas suggests encouraging natural enemies of these insects like lacewings and ladybugs to combat infestation rather than relying on pesticides that can harm or even kill daylily plants.
Daylilies are primarily affected by three diseases: crown rot, leaf streak and daylily rust. Crown rot is found in daylilies planted in long, hot climates. As the name suggests, the plant’s roots rot from bacteria in the soil. Leaf streak will not kill a plant, but does give the foliage a sickly looking appearance. The plant becomes contaminated from diseased soil, and the disease is spread through overhead watering, including rain. Daylily rust is a fungal infection that typically will not harm plants, but also causes unattractive foliage. It is a fairly new condition among daylilies, but is becoming more prevalent especially in the South.
According to Oak Forest Technology Solutions, daylilies can die when they are planted near other larger plants. When daylilies have to compete against shrubs and trees for space, water and nutrients, they will often fail to survive. Roots may die due to overpopulation, or plants may not thrive if water is not readily absorbed.