Small yellow onion

Small yellow onion: how do you recognise it?

Habit

Narrow clump 20–30 cm tall and about 10 cm wide.

Leaves

Narrow, half-round to almost cylindrical and blue-green, with a light waxy bloom.

Flower

Loose heads of hanging, bell-shaped flowers on stalks of unequal length, in June and July. Below the head are two bracts with long, slender points.

Colour

Bright to lemon yellow; the blue-green leaves make the yellow look even fresher.

Bulb

Small, egg-shaped bulb that slowly multiplies by offsets and seed.

Flowering: June–July · Plants: September–November · Pruning: August

Why grow it?

• Bright yellow flowers in June and July, a colour you rarely see among ornamental onions.
• Drought tolerant: ideal for a rock garden, gravel garden or a sunny, dry border edge.
• Bees find nectar and pollen there in early summer.
• Small and dainty: it fits in a stone trough or a narrow strip between paving.
• Little work: no watering, no feeding and rarely any dividing.

Small yellow onion: where does it grow best?

• Full sun: the warmer and sunnier, the better it flowers.
• Sandy or loamy, free-draining soil, neutral to chalky; poor soil is fine.
• Dry: it does not cope well with wet soil, especially in winter.
• Plant in groups of at least ten bulbs, 8–10 cm apart, in a rock garden, gravel garden or at the front of a dry border.

Light

Sun

Soil type

Sand or loam

Acidity

Neutral or chalky

Moisture

Dry

Size

0.3 m tall, 0.1 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Thyme: A low, fragrant mat for the same dry, sunny spot, also popular with bees.
• Blue fescue: Blue-grey tufts that set off the yellow heads beautifully.
• Stonecrop: Covers the ground between the bulbs and flowers later in summer.
• Rock rose: A small shrub that flowers at the same time, in the same dry soil.

Small yellow onion: when and how to plant it?

Plant in September–November.

1. Plant the bulbs in September, October or November.
2. Make sure drainage is good; on heavy soil, mix grit or fine gravel into the top layer.
3. Plant the bulbs 5–8 cm deep, tip pointing up.
4. Space them 8–10 cm apart and plant in loose groups so the effect stays natural.
5. Only water if the soil is bone dry; usually this is not needed.
6. Top the area with a layer of gravel instead of a compost mulch.

Care

Watering

Not needed in open ground. In a pot or trough, occasionally in a dry spring; keep dry in summer.

Feeding

Not needed: on poor soil it stays compact and flowers better.

Mulching

A layer of gravel keeps the leaves dry and the bulbs warm.

Deadheading

Cut the heads off in August if you do not want seedlings, or leave them so it gently self-seeds.

Foliage

Let it wither naturally after flowering and only remove it once it is dry.

Dividing

Only after 4–5 years, when the clump becomes crowded and flowers less.

Tip: Spread a thin layer of gravel around the bulbs: the leaves stay dry, the soil warms up faster and the little yellow flowers stand out nicely against the stones.

Small yellow onion: when to prune it?

Pruning months: August.

When: No pruning is needed. After flowering, in August, cut away the faded heads and the withered leaves.

How:

• Cut the flower stems off just above the ground, or leave a few heads for seed.
• Leave the leaves until they are yellow and dry, then pull them away or cut them off short.
• Keep the spot open and free of rampant neighbours so the bulbs get sun.

Caution: Do not cut the leaves off while they are still green: the bulb needs them to build up its reserves.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Offsets

In August–September, while the plant is dormant, lift the clump, separate the offsets and replant them straight away, 5–8 cm deep.

Seed

Sow ripe seed in autumn in a pot of gritty seed compost left outdoors. Seedlings flower after 2–3 years.

Small yellow onion: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: no protection is needed in a normal Belgian winter.
• Wet is more dangerous than cold: in poorly drained soil the bulbs rot.
• In a pot or trough: in winter, move it under cover or against a wall, out of the rain.

Diseases and pests

• Bulb rot: The bulbs go soft and fail to come up in soil that stays too wet. Replant them in a dry, sandy or gravelly spot.
• Slugs: They eat the young leaves in spring. A layer of gravel partly keeps them off; pick them off in the evening.
• Being swamped: Such a small plant quickly disappears among big neighbours. Keep the spot open and plant it at the front.
• Few flowers: Usually too much shade or soil that is too rich and moist. Move it during its summer rest to a sunnier, poorer spot.

Through the year

• March: Leaves appear. Top up the gravel around the bulbs.
• April: Watch out for slugs.
• May: Flower buds appear.
• June: Flowering begins. Bees on the flowers.
• July: Full flower. No watering needed.
• August: Cut off faded heads and withered leaves. Collect seed.
• September: Plant bulbs. Divide crowded clumps.
• October: Plant bulbs. Sow seed in a pot.
• November: Plant the last bulbs. Move pots out of the rain.

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.

Did you know?

• Flavum is Latin for ‘yellow’.
• It is one of the few yellow-flowered ornamental onions; another well-known one is golden garlic, Allium moly.
• The flower stalks are of unequal length, so the hanging bells sit at different heights: that is why the head looks like a small firework.