The botanical name Hemerocallis comes from Greek words meaning beauty for a day, and that is exactly how each flower behaves. Opening at dawn and fading by nightfall, the blooms are replaced by new buds on the same stem for weeks on end, so a single clump keeps colour going right through summer.
Day lilies are among the toughest perennials you can plant. Here you will find advice on choosing a spot, planting, watering and dividing, along with the pests to watch for and a serious warning for anyone who keeps cats.
Hemerocallis, day lily at a glance
- Botanical name Hemerocallis, grown as species and many thousands of hybrid cultivars
- Common name Day lily, daylily
- Plant type Clump-forming herbaceous perennial, with deciduous, semi-evergreen and evergreen types
- Hardiness RHS H7 for most cultivars (below -20°C), some evergreen types are a little less hardy
- Height and spread Around 30cm to 1.2m tall depending on cultivar, spreading 45 to 90cm
- Flowering Trumpet flowers in yellow, orange, red, pink, purple and cream, June to August, each bloom lasting a single day
- Foliage Arching, strap-shaped mid-green leaves, dying back in autumn on deciduous types
- Position Full sun for the most flowers, tolerates light shade
- Soil Most reasonably fertile soils including clay, best where moist but well-drained
- Good for Sunny borders, banks, mass planting, low-maintenance gardens
Why day lilies cope so well with dry gardens
Beneath each clump sits a mass of thick, fleshy roots that store water. Once established, day lilies ride out the dry summers of eastern England far better than most border perennials, which is why they sit comfortably alongside the plants in our guide to the best drought-tolerant plants for UK gardens.
They flower most freely in full sun, needing at least six hours a day for a good show. In light shade they still grow well but produce fewer buds, and darker colours such as deep red and purple can actually hold their colour better with a little afternoon shade.
Planting pots and bare roots
Spring and early autumn are the best planting times, giving roots several weeks in warm soil before summer heat or winter wet. Day lilies tolerate heavy clay, but dig in some compost to open up very sticky ground.
- Soak bare roots in a bucket of water for an hour or two before planting.
- Dig a hole wide enough to spread the roots out over a small mound of soil.
- Set the crown, where leaves meet roots, no more than 2 to 3cm below the surface.
- Space plants 45 to 60cm apart, or wider for tall cultivars.
- Water thoroughly and keep the soil moist for the first few weeks.
Watering and feeding
In their first summer, water new plants weekly in dry weather. After that, mature clumps rarely need help unless a long drought hits just as the buds are forming, when a deep soak will keep flowers coming.
Too much fertiliser produces lush leaves at the expense of flowers. A light sprinkling of general-purpose feed in spring is plenty, or simply mulch with garden compost each year.
Deadheading and seasonal tidying
Pinch off spent flowers every day or two to keep plants looking fresh, as the faded blooms turn soggy and cling to the stems. When every bud on a stalk has opened, cut the whole stem down to the base.
Deciduous types turn yellow and flop in autumn. Clear the dead leaves in late autumn or early spring, which also removes hiding places for slugs. Evergreen types simply need any scruffy leaves pulled away in spring.
Lifting and dividing
A clump that flowers less after four or five years is usually overcrowded. Lift it in early spring or straight after flowering, then prise it apart with two garden forks pushed in back to back.
Each division needs a fan of leaves and a healthy root section. Trim the leaves back to about 15cm to reduce water loss, replant at the original depth and water in well.
Gall midge, slugs and other troubles
The most frustrating pest is hemerocallis gall midge. Its larvae feed inside developing buds, which swell up, look distorted and never open. Pick off and bin or burn affected buds as soon as you spot them, and do not compost them. Early-flowering cultivars tend to be worst hit, while those flowering from July often escape.
Slugs and snails nibble young shoots in spring, and aphids or thrips sometimes mark the flowers. Daylilies are otherwise trouble-free, rarely suffering from disease in UK gardens.
A serious warning for cat owners
All parts of the day lily, including leaves, flowers and pollen, are highly toxic to cats. Eating even a small amount, or grooming pollen from their fur, can cause acute kidney failure, which may be fatal without fast treatment.
If you keep cats, it is safest not to grow day lilies or bring them indoors as cut flowers. Should you suspect your cat has had contact with the plant, take it to a vet straight away, even if it seems well, as early treatment greatly improves the outcome. Day lilies are not considered dangerous to dogs in the same way.
Planting partners for a summer border
Pair warm orange and yellow cultivars with the purple spikes of salvia or the soft blue of nepeta for a classic contrast. Ornamental grasses such as Stipa tenuissima echo the arching leaves and add movement.
On a sunny bank or along a drive, a sweep of a single cultivar makes a bold statement and smothers weeds. Late-summer sedums carry the season on once the day lilies have finished.
Questions about Hemerocallis, day lily
Are day lilies the same as true lilies?
No. Day lilies belong to the genus Hemerocallis and grow from fleshy roots, while true lilies are Lilium and grow from bulbs. Both are dangerous to cats, however.
Why is my day lily not flowering?
The usual causes are too much shade, an overcrowded clump, planting too deeply or heavy feeding with nitrogen. Move it to a sunnier spot, divide it if it is congested and check the crown sits just below the surface.
Do day lilies spread?
Most cultivars form slowly widening clumps rather than running about the garden. The old orange species Hemerocallis fulva spreads more vigorously by underground runners, so give it room or plant it where it can naturalise.
Can you grow day lilies in pots?
Yes, compact cultivars grow well in containers at least 30cm wide filled with loam-based compost. Potted plants need regular watering in summer and dividing every two to three years.
Day lilies give months of colour for very little work, and they shrug off the dry spells that trouble fussier plants. Browse our perennials collection to find summer companions for them.