Hemerocallis - Planting Design

Things to Consider Before Planting

.Hemerocallis (daylilies) are versatile, hardy perennials which, when given a sunny location, provide many weeks of flowering in the home garden with minimal care.  Hemerocallis are called daylilies, because each individual blossom lasts for a single day. Daylilies have many buds on an individual scape (flower stem), providing a succession of bloom that gives an excellent display in the garden over many weeks.  The modern varieties tend to have many more buds per scape than species daylilies, which extends the duration of bloom in the garden.
Existing species daylilies and all hybridized varieties are categorized into three groups according to the time they bloom during the flowering season (early, mid-season, and late).  Additionally, some varieties flower a second time later in the growing season and they are deemed re-bloomers.
Unlike other herbaceous perennials, some daylily varieties stay green or partially green all winter long (their ancestry comes from species daylilies of subtropical origin).  Others go completely dormant during the winter like a typical herbaceous perennial.  Therefore, daylilies are categorised into a further three groups (dormant, semi-evergreen, and evergreen) based on their degree of dormancy. Varieties (both species and cultivars) that fall into the dormant group die completely back to the ground during winter.  They are completely hardy in areas that have very cold winters.  Those varieties that fall into the semi-evergreen category do not die back completely during the winter, but, show some signs of green growth close to the ground.  These varieties usually survive well during cold winters.  The third group, evergreen varieties, keep their green foliage throughout the winter and tend to be less hardy in areas that get very cold temperatures for extended periods of time.  A good rule of thumb, for a ‘first time’ buyer of any variety of daylily, is to purchase from a hybridiser or grower that has similar growing conditions to your own.
Hemerocallis in Paul Owen's Display Garden Shelby, NC, USA, in front of Berberis Atropurperia; © P. Owen
Hemerocallis in a mixed border in Paula & Chris Dyason's Garden in Histon, Cambridgeshire; © P. Dyason
The final characteristic about daylilies that you need to know before planning which varieties to select for your landscape is their ‘ploidy’ (the number of chromosomes they contain).  It is not necessary to get too technical, but the two basic groups of daylilies available for sale based on their ‘ploidy’ are diploids (containing 22 chromosomes) and tetraploids (containing 44 chromosomes).  All growers provide this information on the cultivars they have for sale.  Why is this important?  Because each group has different characteristics.  The diploid daylilies (which includes species daylilies) are usually more diminutive with thinner, arching leaves.  The flowers are generally smaller and bloom on thin scapes.  The colours of the flowers are subtle and not flashy.  The tetraploid daylilies (because they have twice the number of chromosomes) have the potential for more variation.  The leaves are wider with more substance, the flowers are larger with more intense colouration, and they bloom on much thicker scapes. Tetraploid daylilies usually grow with more vigour.
Note: There are four known varieties of Hemerocallis fulva (an orange daylily originating from East Asia) that are known to exist.  Some are fertile and self-seed, but they all spread by underground stolons (runners).  It has become naturalized in the United States and is considered by some to be an invasive species.  In the UK, it still exists in some historical gardens, but I’ve never seen it for sale here.  It is generally perceived by modern gardeners as a bit of a ‘garden thug.
Exotic mixed planting in Paul Owen's Display Garden; © P. Owen
The vibrant colours of Hemorocallis 'Vitamin C' with hydrangeas in the background; © J. Allnutt
Now That You Have the Basics
.Unlike Hostas (that are usually selected on their foliage characteristics), daylilies are selected based on flower characteristics (size, form. colour, pattern, and scent).  Additionally, there is a great range of scape heights to consider, with the largest scapes reaching a metre and a half or more in height.  Daylilies mix well with other sun loving perennials, annuals, and small shrubs, and stay in tight clumps which need dividing every four to five years. The flowering will diminish if you have waited too long to divide your clumps.  The best time to do this is in the spring or autumn.
Hemerocallis used in a more muted, pastel-coloured border in Paula and Chris Dyason's gadren; © P. Dyason
When Thinking About 'Designing' With Your Plants in a Border
If you want daylilies in your borders that flower all season long, it would be best to use a combination of early, mid-season, late season, and re-blooming varieties.  Because the weather is so variable in the UK., the blooming times might vary year to year.  The time-tested rule for designing a border usually prescribes planting lower plants to the front of the border and graduating to the tallest in the back.; keeping in mind either mixing or contrasting textures, forms, and colour (shades of colour).  Repetition and flow of the plants will carry your eye through your border.   Remember, all the general rules are there to be broken or modified to your own personal taste.  It has become fashionable by some to place ‘not too dense’ tall plants to the front of a border (like wispy grasses) that one peers through for interior views into the border.  Also keep in mind that there should be some evergreen and deciduous structure to provide winter interest when the dormant perennials ‘hide away’ during the cold weather
A broad colour pallet used by Paul Owen in his Display Garden; © P. Owen
More planting in Paul Owen's Display Garden, this time different varieties of hemerocallis planted together; © P. Owen
In Pots or in the Ground
Specimen daylilies can thrive well in pots, but as a rule they generally perform much better when planted directly in the soil.  Daylilies can be used around a pond or water feature, but they prefer not to have their ‘feet wet’ during the winter.   It is especially important to keep the crown of the plant from becoming too wet as that can lead to crown rot.

Where do I obtain my Plants?
Most of your local garden centres will carry a few limited but ‘time tested’ varieties of daylilies.  There are a number of growers in the UK and Europe that provide mail order plants in the spring and autumn.  A list of member growers is on this site.  Commercial growers have websites with colour pictures and descriptions of the varieties on offer.  It is always a great idea to peruse these websites to get ideas of new varieties to try.  Also, don’t forget about friends who might be willing to share a fan or two of their favourite varieties.
The American Hemerocallis Society (AHS) has a database on its website that lists all registered varieties from across the globe (most with pictures).  The AHS bestow several awards every year for outstanding cultivars.  The RHS also has given a number of cultivars an AGM (award of garden merit).  As there are over 70 thousand registered daylilies, the award systems do not necessarily reflect the merits of all the plants available.  Do your research.  Also check out the popularity poll on our website that is taken once a year from a group of our member daylily growers.  There is a wide range of varieties that do well for them here in the UK.  Happy gardening!
Hemerocallis 'Beautiful Edgings' with Sedum 'Purple Emperor' in the background; © J. Allnutt;
Hemerocallis 'Scarlet Oak' with dwarf 'Nandina Firepower' in the background; © J. Allnutt