Also known as: Ornamental Onion

With over 1250 species, allium, the onion plant, is best known as one of the largest plant families in the world. Allium has recently been reclassified into its own family, Alliaceae, although it used to be in the lily family, Liliaceae. Surprisingly, it has a lovely ornamental flower, and yields a number of different cultivars that add color and texture to a springtime garden.

Allium is native to most countries in the northern hemisphere as well as in Africa and Brazil. The many varieties of bulbs are best known as the vegetables onions, leeks, shallots, chives, and garlic, though the whole genus has a strong flavor and scent. Allium has been used for years to flavor food as well as medicinally. The allium bulb used most has been garlic, which is especially beneficial to heart health.

The flower normally grows to about 48 inches tall and spreads to about a foot. When planting bulbs, space the plants approximately 10 to 12 inches apart. The blossoms resemble delicate, airy globes made of tiny, star-like flowers and can be red, purple, blue or white. The stalks are light green and tend to have leaves that spread at the base of the stem. Allium flowers in the late spring and early summer, and the bulbs should be planted in the fall. Make sure you visit your local nursery in the fall to get the type and quantity of allium you want to include in your garden.

Growing Allium

The plant requires full sun and well-drained, fertile soil to grow well. Often, one bulb will generate several offset bulbs that will form clumps of flowers. Plant the bulbs 2 to 4 inches deep in autumn and keep the bulbs dry before planting. Be careful when handling allium – the bulbs can secrete a liquid that will irritate your skin, causing you to need products like aloe vera lotion to calm to ichiness.

Recommended Varieties

There are so many varieties of allium to choose from that what you choose will really depend on your tastes and whether you'd like to harvest the bulbs as food plants. Several varieties can be planted in container gardens. Allium caeruleum has beautiful blue flowers, where allium acuminatum has bell-shaped pastel-pink blossoms. Allium cristophii is a popular purple flower.

Landscape Design Tips

Allium looks lovely in the back of the border or in the center of an island flowerbed. The flowers also look great in an Alpine rock garden or as part of a kitchen garden.

Gardening Zones

Allium is hardy in zones 3 to 10.

Pests and Problems

The plants can suffer bulb rot from fungi or white rot, rust, fungal leaf spots and thrips. It is susceptible to onion fly, meaning you will need to adjust your pest control methods accordingly.