Round-headed leek

Round-headed leek: how do you recognise it?

Habit

A thin, upright, leafless flower stem 50–60 cm tall rising from a small bulb.

Leaves

Narrow, half-round and hollow, grey-green; often wither around flowering time.

Flowers

A dense, egg-shaped head 2–4 cm long, packed with small bells, in July and August.

Colour

Green at first, then wine red to purple from the top downwards; dried, the head stays reddish brown.

Scent

Crushed stems and leaves smell of onion.

Bulb

Small, with a pale tunic; it forms offsets and after a few years a small clump.

Flowering: July–August · Plants: September–November

Why grow it?

• Flowers in July and August, when most ornamental onions are over.
• Bees, bumblebees and butterflies flock to the wine-red heads.
• A lovely cut flower, fresh in a bouquet or dried.
• Takes up hardly any room: the thin stems poke up between grasses and perennials.
• Drought-tolerant and cheap, so ideal for planting by the dozen.

Round-headed leek: where does it grow best?

• Full sun: in shade the stems become floppy and it flowers less.
• Well-drained sandy, loamy or clay soil, neutral to chalky; in wet soil the bulbs rot.
• Dry to moist; in summer it copes with drought extremely well.
• Plant in groups of 20 or more among ornamental grasses and perennials, which give the stems some support.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

0.6 m tall, 0.1 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Feather grass: Fine, swaying stems that the wine-red heads poke through.
• Purple coneflower: Flowers at the same time, with large pink flowers beside the small heads.
• Catmint: A low blue haze at the base that hides the withered leaves.
• Lavender: The same sunny, dry spot, and also a magnet for bees.
• Marjoram: Flowers at the same time and also attracts butterflies.

Round-headed leek: when and how to plant it?

Plant in September–November.

1. Plant the bulbs from September to November.
2. Plant them 8–10 cm deep, pointed end up.
3. Space them 5–10 cm apart, in loose groups or scattered among other plants.
4. On heavy soil: work some coarse sand or grit into the planting hole for good drainage.
5. Firm the soil and water if it is very dry.

Care

Watering

Not needed in open ground. In a pot, keep the compost slightly moist in spring.

Feeding

Not needed: on rich soil the stems become long and floppy.

Leaves

The leaves wither around flowering time; this is normal. Leave them until they are completely dry.

Cutting

For the vase, cut when the heads are half red. For drying, cut them once fully coloured and hang them upside down in an airy place.

Spent flowers

Leave them: the dry heads stay attractive in the border well into autumn.

Tip: Plant the bulbs right among low perennials or ornamental grasses: they hide the withered leaves and support the thin stems. The wine-red heads then seem to float above the border.

Round-headed leek: when to prune it?

When: The round-headed leek is not pruned. At most, you clear away the dry stems in autumn or late winter.

How:

• Leave the spent heads: once dry, they stay attractive in the border for a long time.
• If you do not want seedlings, cut off the heads after flowering, but leave the stem and leaves until they are dry.
• Clear away the dry stems in autumn or in February, before the new leaves grow.

Caution: Only remove leaves and stems once they have completely withered: the bulb is still drawing food from them.

Pruning calendar and basic rules

Propagation

Offsets

Every few years, lift a dense clump in September–October, once the stems have withered. Separate the offsets and replant them straight away.

Seed

In the right spot it sometimes self-seeds. Sow ripe seed in autumn in a pot left outdoors; seedlings take a few years to flower.

Round-headed leek: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: in Belgium no protection is needed.
• In winter, wet soil is more dangerous than frost: make sure drainage is good.
• In a pot: keep it outdoors in a sheltered spot where the compost does not become waterlogged.
• Feel free to leave the dry heads standing: covered in frost, they look lovely in the winter garden.

Diseases and pests

• Bulb rot: The bulbs fail to come up or rot away in wet, heavy soil. Plant in a drier, better-drained spot.
• Flopping stems: On rich soil or in shade the stems become long and floppy. Plant in sun, do not feed and grow it among grasses that give support.
• Withered leaves: The leaves wither during or even before flowering. This is normal; hide them among low perennials.
• Rust: Orange pustules on the leaves, especially in a damp summer. Cut off affected leaves and give the plants a little more space.

Through the year

• February: Clear away last year’s dry stems.
• March: The leaves are growing. Watch out for slugs.
• June: The stems with green buds shoot up. The leaves start to wither.
• July: In flower: the heads turn wine red. Cut stems for the vase.
• August: In flower, full of bees and butterflies. Pick heads for drying.
• September: Plant new bulbs. Divide dense clumps.
• October: Plant 8–10 cm deep.
• November: Last chance to plant.

Edible and useful

Not edible. Ornamental onions are true alliums, related to onion, garlic, leek and chives, and like them they are poisonous to dogs and cats: all parts, especially the bulbs, contain sulphur compounds that damage the red blood cells and can cause anaemia. Cats are more sensitive than dogs, and the signs (lethargy, pale gums, red or brown urine) sometimes appear only after a few days. Horses, sheep and other livestock can fall ill from them too. Even though the leaves and bulbs smell of onion, they are not grown as vegetables: do not eat them, and never store the bulbs with the kitchen onions, as they are not meant for eating and may have been treated with pesticides. Do not plant them where your dog digs, keep loose bulbs out of reach of pets and children, and do not put a vase of alliums where your cat chews the stems. If your dog or cat has eaten a bulb or leaves, call your vet, even if it shows no signs yet. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• In English it is also called ‘drumstick allium’, because its heads look like drumsticks.
• In Britain it is a rare wild plant, found mainly in the Avon Gorge near Bristol.
• It is related to onion, leek and garlic: its stems also smell of onion when crushed.