Millenium Ornamental Onion

Allium ‘Millenium’

Description & Overview

‘Millenium’ is a hybrid allium of unknown parentage, selected for its tidy foliage and 2″ round, rose-purple flowers that bloom July-August. It makes an excellent addition when growing en masse or as part of a border. The name ‘Millenium’ is a nod to the year in which it was developed. Like other ornamental onions, expect yours to attract a range of pollinators like bees and butterflies. Some unwanted wildlife like deer and rabbits typically avoid onions.

Core Characteristics

Mature Height: 12-18 inches
Mature Spread: 12-18 inches
Growth Rate: Perennial
Growth Form: Clumping
Light Requirements: Full Sun
Site Requirements: Average
Flower: Rose-purple
Bloom Period: June-August
Foliage: Green
Fall Color: N/A
Fruit Notes: Not significant

Suggested Uses:

  • Rock Gardens (these plants thrive in well-draining soil. Rocky soils provide great drainage),
  • Border Front (interesting flowers attract attention/sturdy flower stems won’t flop),
  • Cottage Garden (an informal planting where flowers take center stage. A romantic jumble of bulbs, annuals, perennials, flowering shrubs, and climbers),
  • Naturalized Area (the native Nodding Pink Onion, Allium cernuum, will self-seed and spread over large areas),
  • Pollinator Garden (attracts bees, butterflies, and more!)
  • Container Garden (not much room to spread and seed, one single plant will remain small),
  • Cutting garden (unique flowers, fresh or dried, add interest to any bouquet).

Salable #1 Container. Pictures taken late July. Expect different measurements at different times of the year.

Wildlife Value:

Flowers are attractive to bees, butterflies, hummingbirds, and other pollinators. Seeds are attractive to songbirds as a food source. Deer and rabbit resistant.

Maintenance Tips:

This cultivar will not tolerate soggy or waterlogged sites. Water regularly during the first growing season to establish. Pruning off spent blooms will help control the spread of this perennial. Foliage naturally dies back each year and can be removed if needed. Dividing can be done in early spring. While this cultivar has reduced fertility, plants will naturalize and should be deadheaded regularly if this is an unwanted consequence.


While onions in general have no serious issues, there are a few cosmetic (non-lethal) issues that can occur. Bulb rot may occur in soggy or waterlogged sites and is noticed by squeezing the bulbs to feel if they are soft or mushy. Potential insect pests include: aphids, vine weevils, slugs, snails, earwigs, spider mites, and thrips. Thrips are tiny insects that suck plant cells from almost any plant. Damage includes streaks, small white patches, or silvery speckling on leaves. All of these insects can be treated with a few treatments of insecticidal soap.

Leaf Lore:

Millenium Ornamental Onion was hybridized by the breeder Mark McDonough in the year 2000 in Massachusetts. The cultivar name is often misspelled as “Millennium’ despite how Mark McDonough registered the name ‘Millenium’.

This perennial won the 2018 Plant of the Year award given by the Perennial Plant Association and the 2019 Top Performer Perennial award given by Colorado State University.

The genus name Allium comes from the Latin word for ‘garlic’, and the epithet ‘Millenium’ is a nod to the years in which this plant was invented (the year 2000).

The flower bulbs have an extremely strong flavor and can be eaten raw or cooked. The leaves may also be eaten raw or cooked – they add a delicious, strong onion taste to any salad. Medicinally it’s similar to garlic; the entire plant can be used to treat respiratory issues. Juice made from ornamental onions can be used to treat kidney stones, colds, and sore throats. It can also be used to repel moths, biting insects, and moles.

Companion Plants:

Anise-Hyssop, Coneflower, Coreopsis, Gaillardia, Rudbeckia, Cranesbill, Salvia, Shasta Daisy, Little Bluestem, Butterflyweed

All these plants attract other pollinators and have a wide range of colors for either contrast or consistency. Little Bluestem stays in the general size range but adds fall color when allium begins dying back.

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