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More about daylilies

Click on a topic to learn more about daylilies

(See also What is a Daylily?)

What's in a (daylily) name?

Daylilies are named by their originator. Most hybridizers make it a practice to register their daylily introductions with the American Hemerocallis Society (AHS). Each registered daylily name must be unique (that is, each daylily name must be distinct from all others), and certain naming rules must be followed. Other than these few restrictions, hybridizers make their own decisions when it comes to naming their daylilies.

AHS is the official body appointed to register all Hemerocallis cultivars worldwide, and as such, is part of a voluntary system to ensure worldwide uniformity. AHS follows taxonomic rules under the purview of the International Union of Biological Sciences (IUBS), and follows nomenclature rules according to the International Code of Nomenclature for Clutivated Plants (ICNCP-95). For details about naming and registering daylilies, go to AHS Registration Guidelines and Rules (use your back button to return to Loon Song Gardens).

Registration of a daylily name with AHS is a simple and relatively inexpensive procedure. It is not the same as a patent, which is handled very differently and gives the originator legal protection.

Would you like to see if a certain daylily has been registered with AHS? Or are you curious about daylily names? Visit the AHS On-line Daylily Database (use your back button to return to Loon Song Gardens). Note that the newest registrations appear the year following their year of registration.

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These abbreviations indicate time of bloom:

Actual bloom time depends upon your location. In our Minnesota zone 4 garden, daylily bloom season begins in mid-May, when the extra early daylilies start to bloom. Midseason begins about the second week of July, and the very lates begin to bloom in late August. In comparison, peak bloom in Florida is in May, about two months before ours. The daylily bloom season marches northward along the lines of latitude and becomes more compressed in the North, but the season follows the same sequence from one area to another.

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These abbreviations indicate type of foliage:

The hybridizer (or originator) provides daylily foliage type for registration based on how the daylily behaves in their garden. It can be challenging to determine foliage type, and the gardener may observe behavior that differs from the official registration description.

As the season turns. . .

Evergreen and semi-evergreen foliage will show damage from spring frost, but if they are hardy for your climate, these daylilies will rebound with rapid new growth once temperatures are consistently above freezing. By late spring, the gardener can no longer distinguish between these and dormant types.

Spring frosts may damage evergreen and semi-evergreen foliage, making them look unappealing in the early gardening season. At the same time, these foliage types often remain green late in the fall, unlike the dormants.

Consider foliage habit when selecting a planting site

In the North, the fresh shoots of emerging dormant daylilies are exciting harbingers of the coming season. These welcome shades of green and purple bring a barren landscape to life each spring.

If you live in the North and want to have an especially pretty spring garden, consider using dormant daylilies to enhance a spring vignette. As spring blooms fade and ephemerals disappear, the daylilies will fill in and carry the garden into the next season, hitting their stride in summer with a riot color.

At the other hand, you may have an ornamental grass garden that peaks at summer's end, and here you may wish to consider evergreens and semi-evergreens to extend the season.

Should foliage be described only as deciduous or evergreen?

Some growers prefer to use the term deciduous for foliage that dies back completely during winter and evergreen for continuous growers, and they avoid using the semi-evergreen term entirely. Subcategories would be hardy or tender deciduous, and hardy or tender evergreen.

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Foliage type and hardiness

There was a time when growers used the dormant trait to identify a cold-hardy daylily. With the intensive breeding daylilies have undergone, foliage type is no longer considered a reliable measure of cold hardiness in daylilies. Instead of using dormancy as a guide, ask a daylily grower in your area if a particular daylily is suitable for your garden. If they have experience with it, most would be happy to tell you.

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Daylily Flowers

Flower Size

Flowers range in size from miniature to extra large:

Flower Scapes

Flower scapes are the rigid stems that carry the flowers. Scapes range from low to tall. Scapes are typically branched. Scape height and flower size are unrelated, i.e., a miniature flower may be on a tall scape.

Flower Shapes

Flowers may be circular in shape, often with overlapped segments, or they may be triangular in shape. Other forms include the trumpet shape (typical of some of the species), and the star shape (with long, pointed petals and sepals).

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Flower Form

The single daylily flower

The single form of the flower is typical and has six floral segments (or tepals) in all. The outer whorl has three sepals and the inner whorl has three petals. The flower has six stamens with anthers and one pistil. The stamens may be the same color as the petals or may be a contrasting color. At times, the pistil may split, but it is still one pistil.

Recurved form

In the recurved form, floral segments roll under. When a round form with wide segments recurves, people often call it a bagel form, although this is not an official term you will find in registration descriptions.

Flat form

One might say the opposite of the recurved form is the flat daylily, where the flower opens wide and have a very shallow throat. This is an especially interesting effect when the flower has wide and rounded segments that are similar in size.

Double forms

Double daylilies come in several variations. A hose-in-hose or layered double has an extra set or more of floral segments on top of the typical single flower. A peony double has extra tissue growing from the stamens, creating a pompom appearance above the base of petals. These may also have extra sets of petals, resulting in a full peony type of form. In the petaloid, crested or midrib double, extra petaloid tissue grows from the center of the petals.

Polytepal forms (polytepalous)

Polytepal forms have at least one extra petal and sepal (for example, 4 x 4), and some polytepals have more. This trait is often inconsistent, but breeders are currently making progress in this area. Polytepals differ from doubles in that the extra petals and sepals are evenly spaced (and do not lie on top of one another), they have extra stamens, and they develop extra ovary compartments.

Unusual Forms

The Unusual Form (UF) category must have at least three petals or three sepals that twist, curl, pinch, and/or cascade that will often dance in a breeze. Movement and space between segments at the base give the UF its distinctive appearance.


Spiders have very narrow segments. To be registered as a spider, the ratio of petal length to the width must be at least 4.0:1. (To determine the ratio, divide the petal length by its width.) For a number of years, AHS made a distinction between a true spider with a minimum ratio of 5.0:1 and a spider variant, with a ratio of 4.0:1 up to 5.0:1. The spider variant distinction is no longer in use, and all are now in the spider category.

Sculpted Forms

A more recent addition to the daylily lexicon, the sculpted form brings unusual textures and shapes to the daylily flower. Sculpted forms exhibit three-dimensional structural features that can appear at the throat or on the petals and fall into three groups: Pleated, Cristated, or Relief.

Pleated Form: Petals have a deep, longitudinal crease on each side of the midrib.

Cristate Form: Extra petal tissue grows from the midrib or elsewhere. When the tissue grows from the midrib, it is called a Midrib Cristate. This form is sometimes called Cresting and can appear on singles or doubles.

Relief Form: Vertically raised ridges extend from the throat and project from the petal surface.

For further explanation and to see examples of each type of sculpted form, see the AHS Dictionary of Daylily Terms:

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Flower color

Daylilies bloom in a myriad of colors, including many shades of yellow, plus hot orange, rich red, bright rose, soft pink, delicate lavender, cream, near-white, melon, dramatic violet, and regal purple. Tones range from soft pastels to deeply saturated jewel tones.

Selfs, polychromes, bitones, and bicolors

Edges and eyes

More intriguing color patterns

Daylilies may also exhibit contrasting midribs, contrasting tips, dark veining, dots, speckles, and stripe effects. These effects help add ever more interest to the garden display.

Daylily patterns have become a significant goal for many hybridizers. The R.W. Munson, Jr. Award is now given in recognition of the best patterned daylily each year.

All that glitters...

Some flowers exhibit even more unusual effects. You may want to use these daylilies as specimens where garden visitors can have a closer view.

Weather and soil conditions may affect flower color. Daylily hybridizers and growers submit color descriptions for the official Check List based on how the daylily looks in their garden.

Daylily colors often appear deeper and more saturated in the North, especially the jewel tones. Some daylilies registered as pink look more like salmon in our garden, while some pinks are much truer to color.

Cooler temperatures will help bring out some patterns, while at times, heat is necessary. If you are looking for a particular shade of color, it is always best to see what a daylily looks like when growing in your area.

Visit daylily gardens! Check out AHS Daylily Display Gardens, see gardens on a local daylily club tour, take part in AHS Summer Regionals, and go to AHS National Conventions. Visit the AHS Website for more information.

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Rebloom and instant rebloom

Rebloom is indicated in descriptions by the abbreviation "Re." Rebloom means the plant sends up fresh scapes after the initial scapes have bloomed. This trait is often unreliable in a cold climate with a short growing season.

Some varieties send up rebloom scapes while the initial scapes are still present. This is called instant rebloom. This is especially valuable in northern gardens because it lengthens the bloom season.

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Daylilies are sometimes fragrant or very fragrant (indicated in descriptions by the abbreviations “frag.” and “v. frag” respectively). Fragrance in daylilies is subtle and will vary with temperature, humidity, and time of day. Fragrance is often a matter of whose nose is doing the smelling!

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Diploid or tetraploid?

Ploidy is a trait of special importance in daylily breeding.

Chromosomes need to match in number for successful cell reproduction, so the usual approach in breeding is to use diploids with other diploids, and tetraploids with other tetraploids. It is possible for other combinations to be successful due to chromosomal variation, but chances of chromosomes matching correctly are much slimmer, and it can take years if ever to produce seed.

A diploid daylily, the type usually found in the natural species, has 22 chromosomes. The earliest hybrids came from diploids, and diploid breeding continues today.

A tetraploid has double that number of chromosomes, i.e., 44 chromosomes. The earliest tetraploids resulted from chemical conversions of diploids in the late 1930s. The first successful tetraploid daylily bloomed in 1949, and new tetraploids came from subsequent crosses.

These early experiments led to an explosion of tetraploid daylily breeding, which offers many more possible chromosome combinations and has brought out amazing traits in daylilies. Today, the majority of new daylily introductions are tetraploid. Conversions of promising diploid daylilies are still being done, so new genetic material continues to become part of the tetraploid pool.

The gardener does not usually need to be concerned about the ploidy of their daylilies. However, many daylily growers become intrigued by the possibilities of hybridizing, so you might want to make note of ploidy.

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What's new in daylilies?

Hybridizers are constantly working toward clearer colors in all hues, as well as clean green throats, interesting edge and eye colors, and mesmerizing patterns.

True white and true blue daylilies have so far eluded hybridizers, although some near-whites will turn much whiter under a hot sun, and many of the new eye patterns exhibit various shades of blue.

New unusual forms, interesting surface textures, and striking edge effects are the focus of many current breeding programs.

Breeders also continue to pursue good branch structure, high bud counts, reliable rebloom, sturdy scapes, flowers than open well under adverse conditions, plant vigor, cold hardiness, good substance, sunfast colors, and good overall garden performance.

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Daylily Awards, or What do all those award abbreviations mean?

The American Hemerocallis Society (AHS) uses an awards and honors system with trained judges who vote by ballot to determine winners for most cultivar awards each year.

The first step toward the highest award is the Honorable Mention (HM), with about 100 winners each year. After winning an HM, a daylily is eligible to win the second highest award, the Award of Meri (AM)t. Only 12 daylilies can win an AM each year. The highest honor of all is the Stout Silver Medal (SSM). Only ONE daylily wins the Stout each year.

Once a daylily has won an HM, it is eligible to win other Specialty Awards that honor daylilies that excel in a range of categories. Awards change over time, reflecting changes in breeding goals, so some awards have been discontinued while new awards have been added.

Award Abbreviation Key

Pyramid of cultivar awards

Specialty cultivar awards

AHS National Convention Awards (for cultivars seen on a garden tour during the annual national convention)

Note that the year of the award follows award abbreviation in listings.

Visit the American Hemerocallis Society Website for lots more daylily information. Become a member and meet great gardeners who are eager to share their love of daylilies!

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