Star of Persia
Allium christophii ·
Huge, airy spheres, the size of a football, made of metallic, amethyst stars, on short stems in early summer. The seed heads dry in place and last for months.
- Size
- 20 in tall, 10 in wide
- Zones
- 5 to 8
- Light
- Full sun
- Flowers
- Late May to late June
- Pets
- Toxic (moderate)
- Job in a bed
- Accent
A bed built around star of Persia
The planner designed this bed around star of Persia when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 715 that suit those conditions and its dry soil, and says below why star of Persia stands where it does.
The plants
- 1 Moor grass 'Greenlee' × 7, tan
- 2 Cheddar pinks 'Tiny Rubies' × 24, pink
- 3 Stiff goldenrod × 3, yellow
- 4 Purple coneflower × 3, purple
- 5 Dwarf English boxwood × 1, dark green leaves
- 6 Nodding onion × 11, pink
- 7 Star of Persia × 3, purple
- 8 Spring starflower × 8, blue
Why this plant
- Nothing here is unique to it. Its leaf, flower shape and colour are all on the plan already. Its case rests on where it stands and when it performs.
Why here
- Forward of its height. At 20 in it is taller than nodding onion (18 in) behind it, but airy enough to see through.
- 3 plants in 3 places. An accent is a punctuation mark: the repeat along the bed gives it rhythm.
Why now
- In flower for four weeks. From late May to late June.
- Part of the bed's peak. With moor grass 'Greenlee' and Cheddar pinks 'Tiny Rubies' in late May: 3 kinds at once. No week has more.
- Leaves gone by midsummer. They die back and leave bare ground. A perennial that comes up late stands beside it, and grows over the gap.
Planned as an English border: 6 of the 7 groups (86%) are drifts, longer along the bed than they are deep. The flowering is at its height from late May, with 3 kinds out together. Cheddar pinks 'Tiny Rubies' is planted in six places along the bed, which gives it rhythm.
The planner's own design check: 13 Excellent, 4 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where star of Persia goes in a border
At 20 in it belongs in the middle of a bed. In the planner's ten height classes it is medium short (18 to 24 in). It is airy enough to see through, so it can also come forward and veil what is behind it.
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The biggest flower head for the least height, so it can go near the front. The leaves wither as it flowers; grow it through catmint or lamb's ear, which hide them.
- Sculptural globes among low perennials
- Dried seed heads
- Dry, sunny borders
What to plant with star of Persia
Plants recorded as good partners for it, and what each pairing does:
- Catmint 'Walker's Low': in flower together for four weeks, from late May; grows up in time to hide its dying leaves; happy in the same dry soil.
- Salvia 'May Night': in flower together for four weeks, from late May; grows up in time to hide its dying leaves.
- Lamb's ear: its silver leaves are a setting for the flowers, before and after; bold leaves against its medium ones; low enough (12 in) to stand in front of it.
Questions about star of Persia
Does star of Persia need sun or shade?
Star of Persia grows in full sun (6 or more hours of direct sun a day).
It wants dry, sharply drained soil, of average fertility, and little watering once settled.
What zones does star of Persia grow in?
USDA zones 5 to 8. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does star of Persia flower in my zone?
In zone 5 it flowers late May to late June. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 5 | Late May to late June |
|---|---|
| Zone 6 | Late May to late June |
| Zone 7 | Mid May to mid June |
| Zone 8 | Early May to mid June |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should star of Persia be planted?
8 in (20 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 10 in (25 cm), so a group knits into one patch.
It grows 20 in (50 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many star of Persia plants do I need?
At 8 in apart, set out in staggered rows:
- 27 to fill 10 square feet (about 1 m²)
- 16 for a single row 10 ft (3 m) long
- 86 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in three groups.
Is star of Persia poisonous to dogs and cats?
Yes: moderate toxicity to people, dogs, cats and horses. Like all onions, it can damage red blood cells in dogs, cats and horses if eaten. Eating the bulbs in quantity can also upset a person's stomach.
Rated from NC State Extension. Where references disagree, the more cautious rating is used.
What can I plant to hide star of Persia's leaves after it flowers?
A bulb's leaves have to be left to yellow for about six weeks after flowering, to feed next year's flowers. Plant it among perennials that come up late and spread wide, and they grow over the leaves as they fade:
- Catmint 'Walker's Low': 24 in tall and 2½ ft wide, a recorded partner, in flower mid May to mid September.
- Lady's mantle: 18 in tall and 24 in wide, in flower late May to early July.
- Garden chrysanthemum: 24 in tall and 24 in wide, in flower mid September to late October.
What does star of Persia look like in winter?
Star of Persia is underground: it dies back after flowering and waits as a bulb until spring. Mark where it is, so a fork does not find it first.
More Allium
- Allium 'Ambassador' Allium 'Ambassador'
- Allium 'Gladiator' Allium 'Gladiator'
- Allium 'Globemaster' Allium 'Globemaster'
- Allium 'Mount Everest' Allium 'Mount Everest'
- Blue allium Allium caeruleum
- Chives Allium schoenoprasum
- Curly onion Allium senescens subsp. glaucum
- Drumstick allium Allium sphaerocephalon
- Garlic chives Allium tuberosum
- Giant allium Allium giganteum
- Golden garlic Allium moly
- Japanese onion 'Ozawa' Allium thunbergii 'Ozawa'
- Nodding onion Allium cernuum
- Ornamental onion 'Millenium' Allium 'Millenium'
- Ornamental onion 'Purple Sensation' Allium hollandicum 'Purple Sensation'
- Ornamental onion 'Summer Beauty' Allium 'Summer Beauty'
- Pink lily leek Allium oreophilum
- Schubert's allium Allium schubertii
- Sicilian honey garlic Allium siculum
- Turkestan onion Allium karataviense
In these guides
Every fact on record
- Type
- Bulb
- Size
- 20 in (50 cm) tall, 10 in (25 cm) wide
- Plant
- 8 in (20 cm) apart
- Height class
- Medium short (18 to 24 in)
- Place in the bed
- Middle, or further forward: it is airy enough to see through
- Flowers
- Late May to late June; globes; purple
- Leaves
- Medium texture, summer-dormant; green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 5 to 8
- Light
- Full sun
- Soil
- Average, dry and sharply drained
- Water
- Low
- Feeding
- None needed
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.