Star of Persia

Star of Persia: how do you recognise it?

Habit

Bulb with a few broad basal leaves and a single sturdy, leafless flower stem of 40–50 cm.

Leaves

Grey-green, strap-shaped and slightly arching; they yellow before or during flowering.

Flower

A loose, round globe of 15–20 cm with dozens of starry flowers with narrow, pointed petals, in May–June.

Colour

Lilac-purple with a metallic sheen; after flowering the globe dries to a straw-coloured, spiky skeleton.

Scent

Bruised leaves smell of onion; the flowers themselves have hardly any scent.

Bulb

Round bulb with a brown tunic, which forms offsets after a few years.

Flowering: May–June · Plants: September–November

Why grow it?

• Spectacular flower globes of 15–20 cm in May–June, right in the quiet gap between spring bulbs and summer flowers.
• A true bee plant: honeybees, bumblebees and solitary bees collect nectar and pollen from it.
• The faded seed heads stay attractive into autumn and are lovely in dried arrangements.
• Drought tolerant and hardy: once planted, it comes back every year.
• Takes up little room, so it is easy to tuck in between perennials.

Star of Persia: where does it grow best?

• Full sun: this keeps the stems sturdy and gives the best flower colour.
• Well-drained soil: sand, loam or light clay, neutral to chalky.
• Dry to moist; waterlogged soil in winter makes the bulbs rot.
• Plant 20–30 cm apart, in groups of five or more, among lower perennials that hide the dying foliage.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

0.5 m tall, 0.3 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Catmint: Clouds of blue flowers at the base that hide the yellowing leaves.
• Woodland sage: Upright blue or purple spikes in the same sunny, dry soil.
• Feather grass: Fine, swaying stems around the sturdy purple globes.
• Spurge: Lime-green flowers as a fresh contrast to the purple.
• Hardy geranium: A flowering carpet that masks the dying foliage.

Star of Persia: when and how to plant it?

Plant in September–November.

1. Plant in September–November, while the soil still holds some warmth.
2. Loosen the soil and, on heavy clay, work in coarse sand or fine gravel for better drainage.
3. Set the bulbs pointed end up, 10–15 cm deep: about three times the height of the bulb.
4. Keep 20–30 cm between bulbs and plant in groups for the best effect.
5. Firm the soil and only water if the ground is very dry.
6. Mark the spot with a cane, so you do not damage the bulbs when hoeing or replanting.

Care

Watering

Not normally needed. Only water in a very dry spring, while the leaves are green.

Feeding

A thin layer of compost in March is enough; too much fertiliser gives floppy stems.

Foliage

Let the yellowing leaves die back on their own: this is how the bulb builds up strength for next year.

Spent flowers

Leave the seed heads for effect, or cut them and dry them for arrangements.

In a pot

Possible in a deep pot with free-draining compost and a layer of gravel at the bottom; water sparingly.

Tip: Plant it among perennials that fill out in June, such as catmint: they hide the yellowing leaves, and the purple globes seem to float above the border.

Star of Persia: when to prune it?

When: Allium cristophii is not pruned. At most you cut off the dry flower stems in summer or autumn.

How:

• Cut seed heads for dried arrangements in July–August, once they have changed colour and feel dry.
• If you do not want seedlings, cut the heads before the seed ripens.
• Only remove the dead foliage once it is fully yellow and dry.

Caution: Never cut off green leaves: the bulb needs them to flower again next year.

Pruning calendar and basic rules

Propagation

Offsets

Lift a crowded clump in summer, once the leaves have died back, and replant the small bulbs separately in autumn. They flower after one or two years.

Seed

Leave a few seed heads: in a dry, sunny spot it often self-seeds. Seedlings take a few years to flower.

Star of Persia: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: in Belgian gardens it can simply stay in the ground.
• Wet soil is more dangerous than frost: make sure drainage is good.
• In a pot: keep it dry in winter, under cover or against a wall, and wrap the pot in hessian in hard frost.

Diseases and pests

• Bulb rot: Bulbs disappear or turn soft and brown in wet, heavy soil. Plant in a drier spot or on a layer of gravel.
• Slugs: They eat the young leaves in spring. Pick them off in the evening or put a band of coarse grit around the plant.
• Yellow leaves at flowering: This is normal and not a disease. Hide them with perennials in front.
• Few flowers: After years the bulbs become too crowded or too shaded. Lift them after the foliage dies back and replant them further apart in the sun.

Through the year

• March: Leaves appear. Give a thin layer of compost.
• April: Watch for slugs on the young leaves.
• May: Flowering begins. Plenty of bees.
• June: Full flower. Cut stems for the vase.
• July: Foliage dies back. Leave the seed heads or cut them to dry.
• August: Dormant. Lift and split crowded clumps.
• September: Plant new bulbs.
• October: Plant bulbs 10–15 cm deep.
• November: Plant the last bulbs. Mark the spot.

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?

• Allium is the Latin name for garlic: this ornamental onion is related to onion, leek, chives and garlic.
• Each flower globe consists of dozens of separate small flowers, each on its own stalk.
• The dry seed heads keep their shape for years and are sometimes sprayed silver or gold as Christmas decoration.