What are Daylilies?

Daylilies (genus – Hemerocallis) are a herbaceous perennial known for their hardiness, easy care and reliable performance as garden plants. They are sometimes called the “perfect perennial.” The foliage consists of sword like, green leaves arising from a central crown called a division, fan, or ramete. Roots consist of a combination of fine hair roots and fleshy fingerlike growths. Flowers are born on leafless stalks called scapes. Each blossom, as the name indicates, lasts just one day. However, there are often between 20 to 40 blossoms per scape which spread their blooms over a number of weeks. The modern daylilies are available with flow sizes ranging from 2 inches to 10 inches across. Bloom heights vary from 10 inches to over 4 feet. Nearly every color imaginable has been produced with the exception of true blues and pure whites – but you should know there are many AHS hybridizers working on just these goals and they are getting closer every year. While the typical daylily has six petals, there are not many doubles or multi-petaled varieties as well. Also gaining in popularity are the long, thin-petaled “spider” varieties.

History (Index)

Daylilies are native to the Orient. Chinese records indicate that they have been grown as garden plants or as food or medicines for over 4,00 years. The first written records mentioning daylilies are found in manuscripts dated to 2697 B.C.Daylilies were introduced into Europe in the mid 1500s and almost all the species were introduced into American gardens by 1890. The “Father” of the modern daylily was Arlow Burdette Stout. Dr. A.B. stout was director of the New York Botanical Gardens during the 1920s where his love affair with daylilies began. He was the foremost collector and breeder of daylilies in his time and wrote the definitive book on daylily species. The American Hemerocallis Society has named it’s highest award, the Stout Silver Medal, in his honor. Today there are more than 35,000 named cultivars or varieties registered with the American Hemerocallis Society, the international registry of daylilies. the American Hemerocallis Society is a nonprofit, educational group of over 8,000 members, devoted to the promotion, propagation, and advancement of daylilies.

Culture – Growing Daylilies (Index)

Daylilies are some of the easiest of all flowers to grow. Most daylilies bloom best in full sun, but will tolerate some sun. At least 6 hours daily of sunlight is recommended. Red and purple cultivar’s petals absorb more heat in full sun and may not be as sunfast – these can benefit from partial shade during the hottest part of the day. Although daylilies can grow in almost any soil, it is bet to grow them in what would generally be called “good garden soil” with a good quantity of organic matter to retain moisture. They do best with good drainage. Raised beds are desirable therefore in “problem areas.” Daylilies are remarkably drought tolerant, but do best when supplied with frequent watering. An organic mulch of marsh hay, wood chips, etc., is also desirable both as a method natural fertilization as it decomposes, in keeping weeds from getting established and for retaining moisture. If daylilies are fed too much, they will expend energy on creating new fans rather than additional blooms. Therefore light fertilizing is recommended in the spring when growth first shows and again after the peak bloom to foster growth for next year’s bloom season. Newly acquired plants will either come potted or as bare root divisions. Dig a hole such as the crown – where the roots and leaves meet – is at or slightly below soil level. At the bottom of the hole, create a small mound of dirt. Arrange the roots over this mound and fill the hole with dirt. A good watering should be given immediately after planting and the ground should be kept moist for the next week. During the bloom season, if you are not hybridizing, it is recommended that you “deadhead” spent blooms. This not only makes your garden look better, but also prevents unwanted seed pods from forming that can rob some energy from the plants.

Diploids and Tetraploids (Index)

In species daylilies that reproduce by seed there are 22 chromosomes. (There are also a few clones with 33 chromosomes, but these reproduce by vegetative means only and are basically infertile.) Since 1937, an alkaloid isolated from the autumn crocus (Colchicum autumnale), Colchicine, has been used to increase the number of chromosomes in plants. by inhibiting the formulation of spindle fibers during cell division it is possible to achieve polyploid plants. The superiority of induced polyploid plants over their 22 chromosome diploid ancestors led to experiments to induce tetraploid daylilies with 44 chromosomes. Tetraploid daylilies are said to have a number of advantages over diploid daylilies:
Flowers tend to be larger.
Color of flowers are more intense.
Scapes are sturdier and stronger.
Substance both in flowers and leaves is often heavier.
Vegetative vigor in leaves, stems, and flowers is thought to be greater. There are also an increased number of breeding possibilities with the greater number of chromosomes. Meanwhile the diploid varieties continue to charm many with the exquisite flower form, grace, and color. Good pink daylilies are still more prevalent in diploids. Diploids generally set seed more easily. Many find the finer and thinner leaves of diploid cultivars more appealing. Tetraploids have pushed advances in breeding in new directions with wiry gold or silver edges and bubbly and shark’s teeth edging. The miniature and smaller sized daylilies are dominated by the diploids. After many years on the scene tetraploids have failed to displace diploids totally and many a friendly debate still persists as to which ploid is better. Today, there are a great many tetraploid varieties to choose from and it is not necessary to induce new tetraploids to breed them and enjoy them. The extreme toxicity of colchicine has made it no longer available to many gardeners, yet there are still a few dedicated breeders taking the best diploids and converting them to tetraploids. Some of the most exciting new plants in recent years have arisen from newly converted tetraploids.

Foliage Habits (Index)

The winter behavior of daylily foliage is called foliaged habit; habit varies greatly among cultivars. Registered daylilies habits are loosely grouped into three general categories; dormant, semi-evergreen, and evergreen.

Dormant

Dormant daylilies are those whose leaves die back completely as winter approaches. This occurs whether the plant is grown in the North or in the warmer South and is believed to be controlled by the length of the days. A resting bud forms in the crown as the foliage gradually dies down. These buds produce a distinctive spear-like appearance when the emerge in the spring.

Evergreen

Evergreen daylilies retain their leaves throughout the year and continue to grow new leaves all year long. Such habits make them popular with growers in the southern United States. Evergreens form no resting buds. In the North, evergreens will die back from the cold, but if hardy or well mulched will resume growth in the spring. New growth is gradual, without the distinctive spear-like appearance of the dormants.

Semi-Evergreen

Semi-evergreen daylilies are those varieties that display a mixture of the above habits. Many of the species used for early hybridizing did not fall neatly into either category, and the resulting hybrids varied even more. Today, the term is often used to refer to plants that lose their leaves in the north and retain them in the south. Since foliage habit varies depending upon climate conditions under which it is grown, this habit may vary from the description under which it was registered in your location.

Tender versus Hardy, Seasonal Temperature Requirements

The tolerance of daylilies to cold is quite varied. Some are dependably winter hardy in the North, others only do well in the mild climates of the deep South. Others do well in the North if they are mulched so as to avoid repeated thaw-freeze cycles. Cold tolerance is not dictated by foliage habit – there are hardy evergreens and tender dormants although the later are rare as breeders have tended not to use these plants. Tender evergreens are more common since they are favored by plant habit in the south where they achieve no cold test as they mature. Some dormant and semi-evergreens require a cold period to resume normal growth the following year. These plants in the south may gradually decline and can eventually die off. You may wish to check with other gardeners in your area or check with suppliers before choosing plants for your garden. Be aware that there is always a slight risk of loosing some plants that may not do well in your area or did not find conditions favorable in a certain growing season or winter.

Daylily Culture (Index)

Daylilies have long been known as one of the easiest perennials to grow. While this is true to some extent, just like any plant, the better care you provide the better your daylilies will perform. The following is designed to help you better understand daylilies and their needs.

Where to plant?

Q – Should I plant my daylilies in full sun?

Daylilies grow best when planted in full sun to partial shade. In areas that receive less than 6 hours of sun during the day, your daylilies will probably produce fewer and smaller blooms, and the foliage may not be as robust. Here in the deep south, daylilies appreciate having some afternoon shade because of the hot sun. In my yard, I have obtained excellent results by planting in the filtered sunlight under very tall pine trees.

Q – Are there any soil requirements that I should be aware of?

Daylilies will grow in a fairly wide PH range but best results will be obtained if your soil is either neutral or slightly acid. Daylilies will grow in most soil types, but like any other plant, they prefer a soil that is neither too hard or too sandy. Your best bet, especially if you have either a very sandy or hard clay soil, is to add humus when you prepare the soil for planting. One of my favorite forms of humus is composted manure but any good compost will do.

Q – I have a low spot in the yard that collects water after a hard rain. Can I grow daylilies there?

Be sure the place you want to plant has good drainage. If you think you may have a drainage problem, dig a hole about a foot deep and fill it with water. If the water has not drained from the hole after 12 hours, you should probably find another place for your daylilies or build a raised bed filled with good garden soil.

Q – Is there anything else I should watch out for when deciding where to plant my daylilies?

Areas where the daylily roots will have to compete with the roots of larger plants such as shrubs and trees should also be avoided.

When to Plant

Q – What is the best time to plant in northern climates?

In the north, the summers are neither as hot nor as long as in the south so planting in the spring is recommended. If planted too late in the fall, the ground will freeze before the daylily has a chance to become fully established, reducing its chances of survival.

How to Plant (Index)

Q – How should I prepare the soil prior to planting?

You should prepare the soil by digging to a depth of at least a foot. The soil should be loose and any amendments should be well mixed in. One of my favorite tricks is to place a shovel of manure in the bottom of the hole and cover with a few inches of soil. The manure will decompose in the soil and the daylily planted on top will eventually send its roots down to reach the nutrients. I believe this also encourages the roots to grow deep rather than shallow, an advantage here in the hot south.

Q – Should I prune the daylily before planting?

Yes. Trim the foliage to a length of 4-6 inches. This will help the plant compensate for water loss while it’s re-establishing itself. Trim the roots to 6-8 inches in length. This will encourage the plant to send out new roots.

Q – How deep should I set the plants?

Plant the daylily with its roots spread out so that the crown is about one inch deep in the soil (the crown is the area of the plant where the roots all come together). Daylilies planted too deep will not grow properly.

Q – How far apart should I space my daylilies?

Daylilies can be planted as single plants when you are doing a mass planting, or in groups of 2 or 3 together which form clumps. When I plant single plants, I space them about 24 inches apart center to center while I space the groups about 18 inches apart. Because daylilies multiply, planting any closer together will result in them needing to be divided sooner and I don’t like to create any unnecessary work for myself.

Caring for Your Daylilies (Index)

Q – How much water do daylilies require?

Probably the most important ingredient in beautiful daylilies is water. While daylilies can withstand drought because of their fleshy roots, I find it amazing the difference I get when they get all the water they need.
So give plenty of water, at least 1 inch a week. Do not overwater, however, as daylilies do not like to have their roots immersed in water for extended periods of time. Give the soil a chance to drain well before you water again. You may also want to check out my hidden pot trick page for a tip on how to help ensure even watering.

Q – Should I fertilize my daylilies?

Fertilizer is important for healthy daylilies. Proper feeding will result in more and larger blooms and the plants will be more vigorous. In 1995 (a year where I had a good fertilization program) I compare the number of blooms per scape on some plants with the number of blooms from the same plants the previous year (without fertilizer). A few varieties showed very little increase, but the majority increased significantly. The biggest increase was almost 2.5t times the number of blooms as the previous year.

Q – How often should I fertilize?

I recommend that daylilies be fertilized at least twice a year, once in the early spring when the daylilies begin their spring growth, and again at the end of the summer. Here in the south, where we have a long growing season, I also recommend an additional application a couple of weeks after the peak bloom season.

Q – What kind of fertilizer should I use?

I use a granular fertilizer with a 16-18 ratio but any fertilizer that is not too high in nitrogen (the first number) is good. Too much nitrogen will encourage the plants to put out foliage instead of blooms.
Also popular among some daylily growers is a mixture of various nutrients plus an insecticide called the Hooker Formula which is applied to the soil, usually in the spring.

Q – Should I mulch my daylilies?

Daylilies will benefit from mulching. Mulch helps maintain a more consistent soil temperature and also help retain moisture. I no longer apply much right up to the base of the plant, however. To find out why, check out my why did my daylilies stop blooming page.

Q – Are daylilies bothered by insect pests?

Unfortunately, daylilies are not quite as pest and disease free as many nurseries would lead you to believe (almost, but not quite). Pests which will sometime infect daylilies include aphids, spider mites, thrips, slugs and snails. If you find that you need to spray your daylilies you should use something that has been rated for use on daylilies or you know for sure will not harm the plants. I know of a new daylily grower who sprayed all his plants with kelthane for spider mites (kelthane is harmful to daylilies). He didn’t kill his daylilies, but that year he didn’t have very many blooms. If I want to try something new that is not rated for use on daylilies, I will first try it on a single plant (I keep a few plants growing in pots just for this purpose). I use a stronger solution than is recommended and use repeated applications over several months. If the insecticide passes this test, then I feel comfortable using it on the rest of my plants.

Q – What about diseases?

Daylilies are a relatively disease free plant. Crown rot is the only daylily disease that I have had to deal with here in the Salt Lake area. This disease is limited primarily to the deep south and usually only affects a small number of my plants. However, it can kill a daylily in a matter of only a few days.

Dividing Daylilies (Index)

Q – How do I know when my daylilies need to be
divided?

Daylilies multiply by sending up new fans right next to the old fans. If your daylilies have formed a large clump (lots of fans clumped tightly together) and the blooms are smaller or fewer in number than the previous year, you probably need to divide your daylilies.

Q – How do I divide them?

Dig up the entire clump and shake off the dirt. A garden fork works well for this. Separate the plants by either pulling them apart or cutting into individual plants with scissors or knife. When cutting apart a large root with more than one fan growing out of it, try and include an equal amount of root with each fan.

Q – Can I plant the divisions right away?

Yes, I usually do. However, it is recommended that you wait at least long enough for any cut areas to dry before planting.

Q – So, what do I do with the extra daylily
plants?

Give them to your friends, give them to your neighbors, or give them away at work. Daylilies are becoming so popular that I’m sure they’ll be appreciated.

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