Growing daylilies

This plant is a favorite with gardeners as it adapts readily to a wide range of soil and temperature conditions, and is generally quite hardy and free from serious insect problems. It’s an excellent plant for beds and borders, but choose your location carefully as these plants can get rather large (one to three feet in height and across), shading or crowding lower flowers and landscape plants.

Ideally, daylilies prefer well-drained soil and bright, sunny locations. Flowers will open to face the sun or bright light, so place them with this in mind. They will grow in part shade, but wont flower nearly as well. A warm, sheltered, south-facing site may speed up bloom time slightly.

For best bloom daylilies require much fertilizer and moisture prior to bloom time. They will tolerate less fertilizer and poorer soils, but wont bloom as well. Apply granular, organic liquid-soluble, or foliar-applied fertilizers according to label directions.

Although daylilies in pots can be planted almost any time the soil can be worked, early spring and late summer are the best times for digging and transplanting. To propagate, transplant, or divide this perennial, either dig a portion off an established clump or dig a whole clump (they can be large!), then divide. Work carefully to avoid damage to the roots, although some cutting is inevitable. A square-tipped spade works well.

Set the crown (where the root and stem join) no more than one inch below the soil surface, spacing plants at least 18 to 24 inches apart. Be careful not to set plants too deeply since they may become stunted and will lack vigor. When digging the planting hole, leave a mound of soil in the center to spread the roots over, then cover. Most important is to keep new transplants well-watered to a depth of eight to ten inches.

If plants are divided during mid-summer after bloom, cut the tops back to within four to six inches of the base. Keep your new planting weed-free until plants become well established. Best flowering usually occurs two to four years after planting. Mulching around plants with an organic material such as pine straw or ground bark chips will help conserve water and deter weeds.

Once established, daylilies require little care and may grow for many years without division. Yearly addition in spring of compost and fertilizer around plants will help maintain best growth. Some cultivars (cultivated varieties) have foliage that lasts well into the fall and can be cut back then or in the spring. Cut back foliage in late summer or early fall on cultivars whose foliage turns brown. When cutting back, pull off any dead foliage and cut back other leaves to within a few inches of the ground.

Daylilies seldom get serious insect or disease problems in home gardens, although you might encounter three problems. If foliage is damaged as it emerges in early spring, from cold for instance, it may emerge distorted. This is often called “spring sickness”, and plants will usually begin to grow normally with good weather and care.

Often appearing with such distorted leaves, more as a result of them being weakened, is “leaf streak” disease. It appears as brown streaks in leaves, and seems to vary with cultivar. Remove such leaves if heavily damaged, and keep plants healthy.

If ordering from catalogs, inspect plants upon arrival and when planted for rust-colored dots on leaf undersides. Such could be signs of a new “rust” disease, specific to daylilies but similar to those on other plants such as hollyhocks. Remove and destroy any infected leaves.

When choosing which cultivars to plant, in addition to personal preferences, choose those that either rebloom or choose a mix that blooms over a range of time. Visiting local nurseries every three weeks during summer is a good way to get such a mixed selection. Specialty daylily nurseries, and more information on daylilies, can be found on the American Hemerocallis Society website (www.daylilies.org).

Dr. Leonard Perry is Extension Professor, Department of Plant and Soil Science at the University of Vermont. Visit his website at http://www.uvm.edu/~pass/perry/index.html