H. Fulva 'Tawny'
Photo Credit: Tish King

Daylily

Family: Liliaceae

Genus: Hemerocallis

Intro and History

Hemerocallis (hem-er-o-KAL-is) is the scientific name for daylily. The name is derived from two Greek words for “beauty” and “day”, referring to the fact each beautiful flower lasts only one day. Fortunately for daylily lovers, there are many flower buds on each stalk, and several stalks in each clump of plants, so the flowering period lasts a long time. Also, there are many cultivars that have more than one flowering period.

These flowers used to be placed in the lily family (Liliaceae), but are now considered to belong in the Hemerocallidaceae plant family. The daylily originated in China, Japan, Korea and Eastern Siberia. Ancient Chinese people were using the daylily before the development of written language, and earliest records report the flower buds being used for food. The root and crown were used as a pain reliever.

In some parts of China, the primary use of daylilies was on an emotional level. They considered the bright flowers cheerful and uplifting to the spirit. In Chinese literature, the daylily and “forget worry” are synonymous.

Daylilies were introduced to Europe in the 16th century, then made their way to North America during the 17th century. They were a favorite around homesteads because of their beauty, carefree maintenance, vigor, ease of propagation and their being relatively pest and disease free. All these traits that appealed to hardworking pioneers have just as much attraction to busy gardener’s of our time.

Of the dozen or so wild species of Hemerocallis, Tawny Daylily (H. fulva) and Lemon Daylily (H. lilasphodelus) were the favorites, and treasured possessions. Many of these strayed away from the homestead, naturalizing with such ease they were occasionally referred to as roadside weeds in Eastern North America.

In the early 1920’s and early 1930’s, many scientists and amateurs became involved with hybridizing daylilies. English and Europeans created the first crosses, but an American, A.B. Stout, became known as "The Father of the Modern Daylily." His first cultivar, “Mikado”, was introduced in 1929. His extensive breeding programs resulted in some 50,000 crosses and hundred of thousands of seedlings. His research paved the way for other daylily enthusiasts, and now there are thousands of cultivars in a riot of colors, texture, form and size.

In 1946 the nonprofit American Hemerocallis Society was formed. The AHS is an international registry devoted to the promotion, propagation and advancement of daylilies. There are approximately 1,000 new cultivars added yearly. Indeed, daylilies are so easily hybridized and present with such a variety of traits, that many cannot be correctly identified if unlabeled.

Breed Characteristics

Daylilies arise from tuberous, somewhat fleshy roots and make large clumps of narrow, sword-shaped leaves that are evergreen, semi-evergreen, or deciduous, depending on the cultivar. They have large, mostly single funnel-shaped flowers, but there are also some double varieties. Flowers are often fragrant.

The common lemon lily (H. flava) and the tawny orange daylily (H. fulva) are forerunners of the hybrids. The latter bears clusters of large orange flowers. It thrives on neglect, and forms extensive colonies by means of rhizomes. The cultivar ‘Kwanso’ has double flowers.

The older yellow, orange and rust daylilies have been mostly replaced by newer cultivars with wide variations in plant traits. There are taller and dwarf selections now available, from 1’ to 6’ in height. The flowering period is mostly early to midsummer, but some begin in midspring with flushes continuing until frost, thus allowing a choice of daylilies that can provide bloom throughout the growing season.

The flowers range from 3-8” across, some with broad petals, some narrow, and some even have ruffled petal edges. Semi-double and double-flowered forms exist, though singles are still the most common. The colors have expanded beyond the basic yellow, orange and rusty reds to include buff, cream, apricot, and creamy white, and near white, though as of yet, there is no pure white daylily. There are also pink, vermilion, plum or lilac purple, nearly true blue, and some bi-colors. Daylilies often have contrasting eyes or midrib stripes. Many types are sprinkled with tiny iridescent dots known as diamond dust.

Characteristics Describing Daylily Blooms

The foliage of daylilies is described by color, size, habit, cold-hardiness and heat-tolerance. Foliage color ranges from blue-green to yellow-green, or any shade between. The leaves can vary in size from slender and grass like to big, wide and corn like. The length varies from as little as 6 inches long to 36 inches or more.

Foliage habit refers to the winter behavior of daylily foliage. This is loosely categorized as dormant, semi-evergreen, and evergreen.

Daylilies with a dormant foliage habit have leaves that naturally die completely back as winter approaches. They form resting buds at the crown that have a distinctive spear-like appearance as they emerge in the spring.

Semi-evergreen foliage was originally used to describe those daylilies with foliage that retained their leaves and appeared somewhat evergreen when grown in the south, but in the north lost leaves and went dormant. However, today the term semi-evergreen is used to describe any foliage behavior not readily classified as dormant or evergreen.

Daylilies with evergreen foliage habit retain their leaves throughout the year and do not form resting buds. Instead, the produce new leaves continually, unless cold weather inhibits growth. In mild climates, the leaves remain green all winter, but it colder weather, the foliage is frozen back. The crown survives if it is hardy, or well mulched.

Examples

The older daylilies like Hemerocallis fulva and cultivars grow in zones 4-9, making rhizomatous mats, and growing 14 – 48” tall and up to 72” wide. They have large orange flowers in early summer, and make a good perennial groundcover for banks and naturalizing flat areas. It is an aggressive spreader.

H. fulva and H. lilio-asphodelus (Lemon Daylily) are both considered Southern Heritage plants. While the newer hybrids may be showier, the latter species is still cherished for its wonderful perfume and early blossom time. Lemon Daylily is a deciduous variety that grows to 3’ tall, with fragrant, 4” pure yellow flowers in late May or June. It also makes a good ground cover.

H. dumortieri (Dumortier’s daylily), grows in zones 4-8 to 1-1 ½’ tall. It has lemon-yellow fragrant blooms in late spring to early summer that have with brown streaks on the backsides of the petals. As with other old-timey daylilies, it makes a good ground cover.

H. minor (dwarf yellow daylily) is grown in zones 4-8. It is one of the earliest daylilies to bloom, with yellow blooms and low grass-like foliage. It makes a useful edging plant. The bloom time lasts only about 2-3 weeks.

Hybrid daylilies grow in zones 2-10, depending on the cultivars, and can be from 10 – 72” tall. Most prefer sun to part shade. There are so many available, it’s hard to choose just a few examples. On the short end of the spectrum, there’s Hemerocallis x 'Mini Stella' which grows 11” tall and wide with yellow flowers that bloom for a long season starting early summer.

Tall varieties, such as the Hemerocallis 'Autumn Minaret', grow to 72” in height with a 4” fragrant butter yellow blooms with a rosy orange wash. It is a late bloomer that appears after most other varieties have finished blooming.

Search the many cultivars available, and you’re sure to find one that blooms when you want, in the color you want.

Special Features

The daylily is often referred to as the perfect perennial. It comes in a wide range of colors, shapes and sizes. It is able to survive with very little care in a wide range of climates, being drought resistant and almost disease and insect free. It can adapt to various soil and light conditions, fitting into all types of landscapes.

With so many varieties and bloom times, you can select according to early, midseason, or late bloom, and have a long season of flowers. Evening bloomers open toward evening and stay open through following day or longer. Triploids have thick petals and are very weather resistant.

Daylilies work in beds and borders made entirely of daylilies, or they can combine with other perennials such as Shasta daisies, purple coneflowers, red-hot poker, dusty miller, lily-of-the-Nile, and yarrow. They can be massed along driveways and roadsides, in country gardens, or on banks.

They are also a good partner with bulbs such as daffodils, which are up and blooming before the daylily foliage. As the daffodil dies back, the daylily gradually covers that space. This combination can continue for many years, until the daylily root mass becomes too thick to allow the daffodil to emerge, and needs thinned out.

Groups of daylilies work well among evergreen shrubs, near ponds, and along streams. They make a good ground cover on banks for erosion control. Dwarf varieties work well in containers, as edging and low ground covers.

Want cut flowers? Daylilies work for that too. Select cut stems with well-developed buds, and the buds will open on successive days, though each flower is slightly smaller than the preceding one. Snap off the faded flowers daily. Individual blooms also do well in low bowls of water.

And if you don’t like the varieties available to you, you can easily produce your own hybrid!

The bottom line – few plants are tougher, more trouble-free or have more uses than daylilies.

Hardiness

The cold-hardiness of daylilies is variable and not directly related to the foliage habit. Dormant, semi-evergreen and evergreen can be anything from quite cold-hardy to tender.

Tetraploid forms (having double the normal number of chromosomes) often seem more robust and do bear larger flowers than the commoner, stauncher diploids. It’s best to check the hardiness level of the cultivar you want to see if the plant will thrive in your gardening zone.

Growth Habit

Daylilies are commonly 2-3 foot tall. However, there are varieties as low as 10-12” in height and H. Autumn Minaret, grows 72” tall. The plants should be spaced 2-4’ apart, or 3 or 4 plants per square yard on level sites, depending on the variety. For erosion control on slopes, the plant spacing should be halved.

The daylily has four fairly distinct growing parts, the roots, crown, leaves and scape. The roots can be long, slender and fibrous, or enlarged tubers with additional roots at their bases.

The crown of a daylily is the stem of the plant. It is the solid white core located between the leaves and roots. The crown produces the leaves and scapes from its upper surface, and the roots from its sides and lower surface.

Daylily leaves are long and slender. They are arranged opposite each other on the crown, giving a fan like appearance. Multiple fans of a single plant form a clump. These clumps take 5 or more years before they become overgrown and need dividing.

The scape of a daylily is a leafless stalk that bears the flowers. Most have two or more branches that bear several flower buds. Below the branches the stalks have a few leaf like “bracts”. Small plantlets sometimes grow at the junction of the bract and the scape. This is called a “proliferation” and can be rooted to produce another plant.

Bloom Time

Daylilies bloom midspring to fall, according to the variety and the coldness of the climate. Daylily growers use the following terms and abbreviations to indicate bloom time.

To prolong the bloom season, select varieties in different bloom categories, and/or reblooming types. Daylilies that are planted in the shade bloom 2 or 3 weeks later than those in full sun, so you can also prolong the bloom season by varying the planting sites.

Most daylily blooms last for a single day, beginning in the early morning and lasting until the evening. This is called a diurnal blooming type. Nocturnal refers to a daylily bloom that opens late in the afternoon, remains open all night, then closes the following morning or early afternoon. If either the diurnal or nocturnal types remain open at least 16 hours, they are also called extended bloomers.

Propagation

Daylilies are one of the easiest plants to hybridize. To create a hybrid, dab the pollen from the pistil of one kind of daylily onto the stamen of another kind. After pollination, the flower dries up and a seedpod develops. Once the pod turns brown, and begins to split at the far end, the seeds are harvested.

These seeds and naturally forming ones can be collected or purchased from daylily hybridizers. Seed collected from dormant type daylilies should be subjected to cold stratification. This is done by placing the daylily seeds in a waterproof container such as a zip-top plastic bag, then adding a few drops of sterile water. Close the zip top and place the bag in the refrigerator at 32-45 degrees F for at least 3-5 weeks, or until you are ready to plant them.

Alternately, following stratification, the seed can be dried and stored at room temperature until ready to plant.

Seeds from evergreen plants can be directly sown, or handled in the same manner as above. Sow both type seeds in spring or late summer.

Daylilies are also easily propagated by division in early spring or late fall. Lift daylilies out of the ground, and split the clumps into 3 or more fans. If not much dirt came up with the roots, build up a mound of soil and spread the division’s roots wide and down the slope of the mound. Cover the roots with soil, then build a 1” crater around the plant and water it in. When the water settles, more soil may be needed to cover the roots exposed when the water washed soil down to fill air pockets.

Germination or Cuttings

Seeds can be started in either flats or pots and later transplanted, or planted directly in the ground. The seeds need fairly warm soil temperatures for good germination. Plant the seeds between ¼ to ½ inches deep. A good rule of thumb is to plant seeds twice as deep as the seed is fat.

In the deep south, the best time to plant is in early September which allows three months for germination and seedling growth before cool weather sets in. Further north, seeds are often started indoors and grown under lights during the winter months, then transplanted outside in the spring once the ground warms up.

Alternatively, you can root leafy proliferations that form on stems in late summer. Cut the proliferation from the scape. Multiple proliferations can be divided further by cutting before placed in a well-drained potting media. Roots should grow in about a week.

Transplanting

Daylilies can be transplanted at any time of the growing season. There is an advantage, however, to transplanting them during the spring or early fall, because it allows the plants ample time to establish themselves before the next blooming season. Plants are best spaced at least 2’ apart.

Soil

Daylilies will grow in almost any soil, but the better the soil the better the performance. A fertile soil with a balanced pH will yield the best results. Augmenting the soil with well-rotted manure every year or two improves the soil. Fertilizer can be added occasionally, but excess nitrate will lead to rank foliage and poor flowering. Some varieties will grow in damp soil, and in coastal gardens.

Irrigation

Daylilies are drought tolerant. However, regular watering will improve the plant growth, and result in more and better blooms. Water daylilies at the base of the plant to prevent water splashing, and diseases caused by fungus.

Sunlight

Grow daylilies in full sunlight for best results, especially in the north. However, they will also grow in partial shade. Keep in mind the amount of blooms a daylily produces is directly proportional to the amount of sun it gets. The more sun, the more flowers. A half day of afternoon sun will produce the maximum number of blooms. Daylilies receiving morning sun will have fewer blossoms, since the light is weaker. Daylilies will not bloom when grown in the deep shade of trees, unless on the shady side of a house and indirect light is reflected off the building to the daylilies.

Care

Daylilies will grow with minimal care, but will have blooms of even better quality with a little extra attention. They do best when grown in soil with ample humus. Use a low nitrogen fertilizer in early spring and again when the flower scapes appear for best bloom. A 5-10-15, 6-12-12, or 5-10-10 analysis works well.

Keep the plants well- watered when they are actively growing in the spring and summer. A mulch around the base of the plant will conserve moisture and discourage weeds. Pine straw, sawdust, decomposed leaves or grass clippings, wood shavings, and spent mushroom compost are examples of suitable compost.

Avoid cultivating deeply around daylilies, as the fleshy roots grow near the surface and can be damaged.

Removing dead leaves in the spring, and deadheading spent flowers will improve the appearance of the plant and help prevent disease.

Pests

For the most part, daylilies are pest free. There may occasionally be a problem with trips, aphids, spider mites or four-lined plant bugs. Using an appropriate insecticide should quickly eradicate the problem.

Disease

Nutritionally and water stressed daylilies are more susceptible than healthy, vigorous plants and may have an occasional problem with fungi or leafspot. The foliar disease known as yellows disease or daylily leaf streak is cause by the fungus Aureobasidum microstictum. It causes small reddish-brown or brown spots, and then a central yellow streak beginning at the leaf tip along the midvein. In severe cases, the entire leaf will turn yellow. The disease does not affect blooms. Cultivars vary on susceptibility to this fungal disease.

To prevent fungal disease, water early in the day so leaves have a chance to dry since fungal spores are released when foliage is wet. Keep the plants well-spaced to allow air movement around the plants. Remove infected leave debris. A fungicide labeled for leaf spot diseases can be used.

Daylily rust is not a new disease for daylilies, but was first seen in the US in 2000. Due to widespread shipping of plants, the disease spread quickly. It is caused by Puccinia hemerocallidis and appears first as small, yellow spots and streaks on upper leaf surfaces. The rust becomes a raised yellow-orange to rust-brown pustule on the underside of the leaf that can easily be seen with a small magnifying glass. Running a white tissue over the surface of the pustules is a good test, as daylily rust will leave a stain from the orange-yellow spores. The infection can affect the leaves and scapes, but not the tubers.

Fungicides may help the problem. It is generally recommended to remove the foliage from all plants discovered to have rust, cutting just above the soil level. For those who do not wish to use fungicides after the initial cutting back, treatment may be limited to continuous removal of infected leaves as they are noticed. Removed leaves should be destroyed, preferably by burning or burying where this is possible. Fungicide applications will not be as effective if the foliage is not removed from the plants.

One way used to prevent this disease is to isolate new plants until it is positively known they are not carriers of daylily rust. However, they must be kept far enough away from other plants to prevent windborne spread of the disease. Rust spores can travel long distances on air currents. The current timeframe thought best for isolation is six months.

Another way some growers are trying to prevent rust from being introduced into their gardens is by peeling the outer layers of leaves from new daylily plants right to the crown, then cutting the rest about one or two inches above the crown. The plant can then be soaked in fungicide if desired. However, this routine may add to transplant and shipping shock of new plants, so that risk must be balanced against the desire to prevent introducing rust into the garden.

One other problem sometimes found with daylilies is “spring sickness”. Early foliage may be yellowed and crumpled. It is believed to be a nutrient deficiency caused by daylilies pushing up early in the spring while the soil is still cool and microbial activity is low, so nitrogen is not easily available. Generally speaking, the daylilies green up later on their own as the soil warms up and nitrogen becomes more readily available.

Additional Info

The most prestigious award presented by the American Hemerocallis Society annually to a daylily breeder is the Stout Silver Medal, in honor of Dr. A.B. Stout. Other awards are designated by AM, the Award of Merit, presented to ten selections each year. Honorable Mention (HM) is awarded to any plant receiving ten or more votes from the selection committee. SM stands for Stout Medal, the highest award a daylily can receive. SM winners include the long-blooming dwarf yellow ‘Stella De Oro’ and the free-blooming yellow tetraploid ‘Mary Todd’. An old garden type that retains its popularity amid the influx of new hybrid daylilies is “Hyperion’, a 4’ tall plant with fragrant yellow flowers that bloom in midsummer.

References

Reader’s Digest (April 1983). Illustrated Guide to Gardening. Pleasantville, NY. The Reader’s Digest Association, Inc.

Brooklyn Botanic Garden. Bush-Brown, Louise and James (1996). America’s Garden Book. New York, NY. Macmillan.

Fell, Carolyn & Derek (1995). Step-by-Step Sun Gardening. Harrison, OH. Springhill Nurseries.

Macunovich, Janet (1996). Caring for Perennials. Pownal, VT. Storey Publishing.

Southern Living. (1998) The Southern Living Garden Book. Birmingham, AL. Oxmoor House, Inc.

The American Hemerocallis Society Accessed 2006-09

Australian Daylily Society Accessed 2006-09

EZdaylily.com Accessed 2006-09

University of Kentucky. Hemerocallis (Daylily) Propagation. Accessed 1006-09