Allium

Plant of the Week April 17, 2023

Allium (Allium spp.)

Genus Common name; Allium, pronounced: AL-ee-um.  

Ornamental onion. Alliaceae (onion)

By Jeanette Siddons, Anoka County Master Gardener

For the gardener who wants an easy-to-grow and carefree perennial, this is your plant! Alliums grow in zones 4-9 and bloom between June and August depending on the variety. They have compact green stalks that grow 8-24 inches tall with a spread of 16-20 inches wide. Flowers bloom at the tip of green-bladed foliage. They come in various colors: purple, violet, pink, and rosy purple. The onion-like scent will help keep deer and rabbits away. This tidy plant is perfect for mass plantings, borders, or on its own. It can also be used as a thriller in containers.

Allium maintenance is simple. They tolerate most soil pH levels. They thrive in full sun with evenly moist conditions, but they will not do well in standing water. Use a slow-release fertilizer each spring. Prune the plant back when the flowers are spent and the blades are yellowed. After blooming, it is normal for the plant to go dormant during the hottest part of the summer. Remove the yellowed leaves as needed, or use another plant near it to hide the yellowing foliage. Some great companion plants are coreopsis, blanket flower, and coneflower. If you use allium in a container, be sure to transplant it into the ground by early fall to protect it over the winter. Continue to water as normal until the ground freezes.

Some popular hybrid varieties include Allium Summer Beauty, Millenium, Serendipity, and Medusa. Plant multiple varieties, it’s possible to stagger the bloom times from mid-June through mid-August. Check each plant for specific growing information.

Information found at these sites; Gertens, Minnesota State Horticulture

Society, Northern Gardener Magazine, and Walters Gardens