How to grow ornamental onion (Allium hollandicum)

Allium hollandicum · Allium, Persian onion, Dutch garlic

Ornamental onion (Allium hollandicum) — bulbous perennial from Iran and Central Asia with strap-shaped grey-green leaves and dense round heads, about 10 cm across, of star-shaped violet flowers on stems up to 1 m tall in late spring and early summer. The leaves die down by the time it flowers. Ornamental onion grows best in full sun.

Updated: October 28, 2026

When to plant ornamental onion?

Plant in autumn, about a month before your first autumn frost, so the roots grow before winter; it flowers or crops the next season.

Dates for your city are on the frost dates page.

Frost dates · When to plant

Quick facts

Type	Flower
Latin name	Allium hollandicum
Family	Amaryllidaceae
Also called	Allium, Persian onion, Dutch garlic
Planted as	bulbs
Life span	perennial
Planting season	autumn
Light	Full sun
Frost	tolerates light frost
Growth starts	150 days after planting
First flowers	76 days after growth starts
Flowering lasts	21 days
Grown in	Open ground, At home

How long does ornamental onion take from planting to flowering?

From planting to the first flowers: about 226 days, or 32 weeks.

Step	Day
Planting	0
Growth starts	150
First flowers	226
End of flowering	247

Days count from the day of sowing or planting, by the figures of the card.

Where does ornamental onion grow?

1,773 records of the plant in gardens, fields and the wild worldwide; most photos come from Norway, Denmark, Austria, Germany, and United States.

World map: where ornamental onion has been recorded — Darker green means more records. Photos are real observations from those countries — tap one to see it. Map and records: GBIF.org (2026-10-28), © OpenMapTiles © OpenStreetMap. Photo: Rune Moe, Rožánek,R. (CC BY / CC0).

Ornamental onion, Norway — Darker green means more records. Photos are real observations from those countries — tap one to see it. Map and records: GBIF.org (2026-10-28), © OpenMapTiles © OpenStreetMap. Photo: Rune Moe, Rožánek,R. (CC BY / CC0).

Ornamental onion care by growth stage

Open ground

Stage	Watering	Temperature	Feeding
Growth	—	—	—
Flowering	—	—	—

At home

Stage	Watering	Temperature	Feeding
Growth	—	—	—
Flowering	—	—	—

Growing notes

Light

Full sun in a sheltered spot, so wind does not blow the tall stems over. It tolerates part shade, but flowers best in full sun.

Soil

Free-draining soil. Bulbs rot in cold, exposed or waterlogged sites; do not plant into freshly manured ground. On heavy clay grow it in deep pots of gritty compost.

Care

Plant bulbs in early to mid autumn, about four times as deep as the bulb is wide and at least 20 cm apart. In the ground it is drought tolerant and needs neither watering nor regular feeding — summer watering can rot the bulbs; pots need water but must not become waterlogged. The leaves fade as the flowers open, so plant it behind other perennials. Cut off spent heads to stop self-seeding, or leave them as dried decoration. After the leaves die down, lift crowded clumps and detach the offsets. Avoid beds where onions grew — it shares their pests and diseases, such as onion fly, allium leaf miner and downy mildew.

Pests and diseases of Ornamental onion

3 problems are recorded for ornamental onion; each has a page with symptoms, treatment and prevention.

Diseases

Pests

Onion fly: Seedlings collapse and die; one maggot can kill several neighbouring seedlings.

Other plants of the Amaryllidaceae family

Ornamental onion belongs to Amaryllidaceae; 10 other plants of this family have a guide here.

Plant lists it is in

Part of: Garden flowers · Perennial garden flowers · Bulbs to plant in autumn

Sources

Figures checked against these sources.