Ornamental onion 'Millenium'
Allium 'Millenium' · Amaryllidaceae Popular
A clump-forming onion that behaves like a perennial: glossy, grassy leaves all season and rosy-purple globes for a month in late summer. It does not seed about.
- Size
- 18 in tall, 16 in wide
- Zones
- 4 to 8
- Light
- Full sun
- Flowers
- Mid July to late August
- Pets
- Toxic (moderate)
- Job in a bed
- Drift
A bed built around ornamental onion 'Millenium'
The planner designed this bed around ornamental onion 'Millenium' 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 966 that suit those conditions, and says below why ornamental onion 'Millenium' stands where it does.
The plants
- 1 Ornamental onion 'Millenium' × 3, purple
- 2 Cheddar pinks 'Tiny Rubies' × 26, pink
- 3 Heath aster 'Snow Flurry' × 5, white
- 4 Little bluestem 'Standing Ovation' × 3, tan
- 5 Italian bugloss 'Dropmore' × 3, blue
- 6 Dwarf English boxwood × 1, dark green leaves
- 7 Hyacinth 'Delft Blue' × 8, blue
- 8 Schubert's allium × 4, pink
Why this plant
- The only purple.
Why here
- At the back. At 18 in it is seen over Cheddar pinks 'Tiny Rubies' (4 in) in front of it, and has nothing behind it to hide.
- A step in the back row. Next to dwarf English boxwood (2½ ft) and Italian bugloss 'Dropmore' (4 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for six weeks. From mid July to late August.
- Fills a gap. For three of those weeks nothing else on the plan is in flower.
Planned as an English border: 4 of the 5 groups (80%) are drifts, longer along the bed than they are deep. The flowers stay on the cool side of the palette: purple, pink, blue, white and tan. Cheddar pinks 'Tiny Rubies' is planted in 7 places along the bed, which gives it rhythm.
The planner's own design check: 11 Excellent, 6 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 ornamental onion 'Millenium' goes in a border
At 18 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
Unlike the spring alliums its leaves stay fresh all season, so it can sit at the front. The globe shape repeats well: dot several groups along the edge to tie a bed together.
- Late-summer globes for the front of a sunny border
- Pollinator gardens
- Neat edging
What to plant with ornamental onion 'Millenium'
Plants recorded as good partners for it, and what each pairing does:
- Sedum 'Autumn Joy': in flower together for two weeks, from mid August; bold leaves against its fine ones.
- Catmint 'Walker's Low': in flower together for six weeks, from mid July; spires rising out of its mound.
- Black-eyed Susan: purple against yellow, opposite each other on the colour wheel, in flower together for six weeks.
Questions about ornamental onion 'Millenium'
Does ornamental onion 'Millenium' need sun or shade?
Ornamental onion 'Millenium' grows in full sun (6 or more hours of direct sun a day).
It wants ordinary well-drained soil, of average fertility, and little watering once settled.
What zones does ornamental onion 'Millenium' grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °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 ornamental onion 'Millenium' flower in my zone?
In zone 5 it flowers mid July to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Late July to late August |
|---|---|
| Zone 5 | Mid July to late August |
| Zone 6 | Mid July to late August |
| Zone 7 | Mid July to mid August |
| Zone 8 | Mid July to mid August |
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 ornamental onion 'Millenium' be planted?
12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 16 in (40 cm), so a group knits into one patch.
It grows 18 in (45 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many ornamental onion 'Millenium' plants do I need?
At 12 in apart, set out in staggered rows:
- 12 to fill 10 square feet (about 1 m²)
- 11 for a single row 10 ft (3 m) long
- 38 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is ornamental onion 'Millenium' poisonous to dogs and cats?
Yes: moderate toxicity to dogs, cats and horses. Like all onions, it can damage red blood cells in dogs, cats and horses if eaten.
Rated from NC State Extension and the ASPCA. Where references disagree, the more cautious rating is used.
What flowers after ornamental onion 'Millenium'?
Ornamental onion 'Millenium' is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:
- Sedum 'Autumn Joy': from mid August to mid October, 24 in tall (a recorded partner).
- Garden chrysanthemum: from mid September to late October, 24 in tall.
- Autumn moor grass: from mid August to early October, 16 in tall.
What does ornamental onion 'Millenium' look like in winter?
Ornamental onion 'Millenium' dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
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 '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
- Star of Persia Allium christophii
- Turkestan onion Allium karataviense
In these guides
Every fact on record
- Type
- Perennial
- Size
- 18 in (45 cm) tall, 16 in (40 cm) wide
- Plant
- 12 in (30 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Mid July to late August; globes; purple
- Leaves
- Fine texture, herbaceous; green
- Shape
- Mounding, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Amaryllidaceae
Checked against NC State Extension and ASPCA poison lists. 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.