Daylilies: choosing varieties, planting, dividing clumps and a warning about cats

In short: The daylily (Hemerocallis) is a hardy perennial whose individual flowers each last one day, but the clump flowers for several weeks. It flowers best in sun, tolerates partial shade and almost any soil. Clumps are divided after 3–4 years. It is deadly poisonous to cats and threatens their kidneys.

The daylily is a perennial for people who want a bed that looks after itself. It survives heat, drought and heavy clay, needs no supports, slugs will not destroy it, and it lasts for years in one spot. The Latin name Hemerocallis means "beauty for a day": each flower opens in the morning and wilts in the evening, but dozens gradually open on a strong stem.

Below you will find how to choose a variety, where and how to plant a daylily, how to divide it and why you need to be careful if you have a cat at home.

Species and varieties: how they differ

Garden centres mainly sell hybrids, with thousands of registered varieties. When choosing, it pays to look at four characteristics, not just colour.

Of the botanical species, mainly the yellow daylily (Hemerocallis lilioasphodelus) is grown, which flowers early, in May and June, and has a pleasant scent. The orange daylily (Hemerocallis fulva) with orange flowers spreads by underground runners and is too invasive for a small bed; it suits a slope or the edge of the garden better.

Daylilies can also be grown from seed, but seedlings of hybrids do not come true to the parent plant and flower only after 2–3 years. Buy a specific variety as a plant and propagate it by division.

Where to plant a daylily

It gives the most flowers in full sun. In partial shade it grows well, it just produces fewer stems. Dark red and burgundy varieties appreciate afternoon shade; in strong sun their flowers may fade.

It is undemanding about soil. It tolerates even poorer and heavy clay soil, but does best in fertile, well-drained soil that does not dry out completely in summer. It suits perennial borders, the bases of trees with a thinner canopy, slopes against erosion and the edge of a pond, as long as the roots do not stand in water. For tips on combinations with other perennials, see the article ornamental perennials.

Planting step by step

1. Timing: spring (April to May) or early autumn (September). Container plants can also be planted in summer if you water them regularly.
2. Hole: twice as wide as the root ball; loosen the bottom and mix in compost.
3. Depth: the crown, where the leaves grow from, must be at ground level. A daylily planted deep grows but flowers poorly.
4. Roots of bare-root plants should be spread over a mound of soil in the middle of the hole.
5. Spacing: 45–60 cm. Groups of three or five plants of the same variety are more impressive than single clumps.
6. Watering: water generously straight after planting and do not let the soil dry out during the first month.

Care through the year

• Spring: remove last year's dry leaves and scatter compost or general-purpose fertiliser around the clump. No more nutrients are needed; an overfed daylily produces leaves instead of flowers.
• Summer: snap off the closed, faded flowers; the clump looks tidy and mould does not hold on it. After the whole stem has finished flowering, cut it to the ground so the plant does not invest in seed. In a long dry spell water generously once a week; mature clumps survive drought but flower for a shorter time.
• Autumn: dormant varieties turn yellow after frosts. You can cut the leaves off or leave them until spring as a natural blanket.
• Winter: they need no protection. Cover evergreen varieties lightly with evergreen branches in bare frosts.

In a container a daylily grows if it has at least 30 litres of compost. Water regularly and feed from spring until July; in winter move the container against a wall.

Dividing clumps

After 3–4 years the clump becomes crowded, thins out in the middle and the flowers decrease. That is the time to divide it.

1. Dig the clump up in spring when the leaves are shooting, or straight after flowering in August.
2. Shake off or rinse off the soil so you can see the individual rosettes of leaves.
3. Divide it by hand, with two spades pushed in back to back, or with a sharp knife. Each piece should have at least 2–3 rosettes and healthy roots.
4. Shorten the leaves to 15–20 cm so they lose less water.
5. Plant the pieces immediately and water. They usually start to flower the following year.

Pests and problems

The daylily is one of the healthiest perennials, but a few problems may appear.

• Hemerocallis gall midge (Contarinia quinquenotata): the buds are shorter and conspicuously swollen, do not open and rot, with tiny whitish larvae inside. It does damage from the end of May to the beginning of July. Pick off affected buds as you go and dispose of them in household waste, not in the compost. Late-flowering varieties usually escape, because they set buds only after the egg-laying period.
• Slugs nibble the leaves as they shoot in spring. The damage is usually small, but protection helps young plants, see fighting slugs in the garden.
• Aphids and thrips suck on the buds, and the flowers are then often spotted or deformed. The article whiteflies, aphids and spider mites describes how to deal with them.
• Few flowers: most often shade, planting too deep, an overcrowded clump or too much nitrogen.
• Brown streaks and yellowing leaves in summer: often drought or natural ageing of the leaves; pull out the dead leaves.

Daylilies and cats: a serious risk

The ASPCA lists daylilies among the plants that can be fatal to cats. All parts are dangerous: leaves, stems, flowers, roots and pollen. A small piece of leaf, pollen licked from the fur or water from a vase of cut flowers is enough. Poisoning shows as vomiting, loss of appetite and lethargy and can lead to kidney failure. This kidney damage is not described in dogs.

If your cat goes into the garden, consider whether to plant daylilies, and never put them in bouquets in a flat with a cat. If you suspect your cat has chewed the plant, go to the vet straight away, not only after symptoms appear. Early treatment is decisive.

Frequently asked questions

When should I plant daylilies?

Best in spring (April to May) or in early autumn. Plants from containers can also be planted in summer, you just have to water them regularly until they root.

Does a daylily tolerate shade?

Partial shade yes; in full shade it grows but flowers little. For abundant flowering it needs sun for at least half the day.

Why is my daylily not flowering?

The most common causes are shade, a crown planted too deep, an overcrowded old clump, an excess of nitrogen or recent division. Divided plants usually flower weakly in the first year.

Is the daylily poisonous to cats?

Yes, very. According to the ASPCA, all parts of the daylily including pollen can cause kidney failure in cats. If you suspect chewing, go straight to the vet.

When should I cut daylilies?

Cut the faded stems to the ground straight after flowering. You can cut the leaves of dormant varieties in autumn after they turn yellow, or leave them until spring and tidy them up when the new growth shoots.

How often should I divide daylilies?

Roughly every 3–4 years, when the clump gets crowded and flowers less. Divide in spring as it shoots or after flowering in August.

Recommended products

• BIOPON general-purpose fertiliser 1 kg – a single spring feed for the clump; a daylily does not expect more nutrients.
• Pointed spade SOLID FISKARS – for digging up and dividing an old dense clump.
• Planting trowel – for planting divided pieces and smaller plants.
• FISKARS shears for herbs and flowers – for cutting faded stems to the ground.

Sources

• Royal Horticultural Society: How to grow daylilies
• Royal Horticultural Society: Hemerocallis gall midge
• ASPCA Animal Poison Control: Day Lilies
• ASPCA: Which Lilies Are Toxic to Pets?

Updated: 27 September 2026