How to Grow Hemerocallis, common name Day Lily

Hemerocallis, common name Day Lily, is a spectacular summer flowering plant. Each plant has multiple stems with many flower head, ensuring constant flowers throughout the summer, even though each flower lasts for only one day.

Day Lillies are fully hardy (mostly) herbaceous perennials return reliably each year. Day lily vary in size from small compact varieties of around 30cms to the taller varieties of up to 1.5m. Hemerocallis is long flowering with large trumpet-shaped flowers, often with stripes and attractive clump forming foliage. Even though each individual flower is short lived, the plant will be in flower for around 4-6 weeks. The name Hemerocallis means 'beautiful for a day'.

Many Day Lilies are herbaceous, which means they die back completely in the winter leaving bare earth and emerge in the spring with fresh growth. In milder areas, they can be evergreen or semi-evergreen.

How to plant Day Lillies

Day Lillies flower best in full sun but will tolerate partial shade. Ideal growing conditions are well drained fertile soil but Hemerocallis will tolerate heavier soils and once establish have some resistance to drought.

The reason I tagged Day Lillies as an amber wheelbarrow plant is although easy to grow, they require some maintenance.

The taller, larger Day Lilies will need to be staked. The new growth may look very upright as it emerges, but don't be fooled, the taller varieties of Day Lily look much better with some staking and support. In spring, (or when you get round to it,) as the growth emerges, place a support under their foliage to keep the plant upright and stop it collapsing later in the season when there are many blooms.

In terms of maintenance, Day Lilies need to be dead headed regularly to keep the plant looking good. Each stem has multiple flowers, which is good in the sense of making the plant attractive, but it means dead heading as the flowers are short-lived they need to be removed regularly to keep the plant flowering. After flowering, each stem can be cut to the ground. Once the plant has flowered and the foliage looks tatty, cut the foliage to the ground and it will reward you with fresh lush growth for the rest of the summer, although it will not flower again.

The plus side is that day lilies flower constantly from late spring to early- mid summer, with strong lush foliage and make excellent border plants. They form large clumps, see third image above, and produce good strong colour. They look spectacular, producing large trumpet-shaped flowers in varying shades of yellow, orange, red and deepening down to crimson.

Day Lilies make an excellent cut flower.

Contarinia quinquenotata gall midge damage on Hemerocallis flower bud

Hemerocallis gall midge

The image left shows Contarinia quinquenotata, common name gall midge damage on Hemerocallis flower bud. It was first observed in the UK in 1989 and is now fairly widespread. Day Hemerocallis gall midge does attack Lily flowers. This is a tiny fly that lays eggs in the flower bud between May and mid-July. The larva feed on the developing flowers buds, causing buds to become deformed or not open. The fly is only active until mid-July, later flowering varieties are not affected.

Credit for this very helpful image goes to Richard Avery on Wiki. You can clearly see, and I have annotated, the long unaffected bud with a cluster of shorter deformed buds which have been affected by the gall midge.

The larva are hard to see, being translucent. It is difficult to treat. Picking off the galls by hand is the best option, as is picking off all affected buds to try to arrest the spread.
The problem with using chemical controls is it will adversely affect visiting bees and pollinators, and not recommended.

Day lilies are an amber wheelbarrow plant as they need some attention and division with time, so not entirely maintenance free.

How to Divide Day Lillies

To keep Day lilies flowering at some point, usually around every three/four /five years, the plants need to be divided because they become congested. The only way to do this is to dig up the plant, divide and replant. If you have day lilies which don't seem to be flowering as well as they did, this could be the problem.

The image shows the congested clump of day lily which has been dug up and place on a tarpaulin ready for division. Divide a clump by using a small saw and cut it into pieces. Then replant, the best pieces, all of which is hard work. The time to divide is late autumn or spring.