The allium is a member of the onion family. This plant is known for its very ornamental and showy nature. Flowers are ball shaped with tiny florets that can range from two to ten inches in diameter on stalks that can range from 6” to 5’. It makes for a very fragrant cut flower. Although, there are some with an onion odor that need to be bruised or cut to give it off.
Fall is the best time to plant these bulbs. Plant 2-4 inches deep in a well-drained soil. Depending on the variety, bloom times can range from spring to late summer. If left in the ground, these bulbs should be mulched in the fall.
A few alliums to consider are:
A. giganteum (Giant Allium). These bloom in the summer and produce softball size clusters of bright lilac flowers, with stalks that are up to 5’ tall. A. karataviense (Turkestan allium). These bear large clusters of flowers in mid-spring. Colors range from pinkish to beige to reddish lilac.
Smaller alliums that could be grown in rock gardens or as borders include:
A. oreophilum (A. ostrowskianum). This beauty of an allium produces loose clusters of rose-colored flowers on 8-12 inch stems and blooms in late spring.
A. moly (Golden Garlic) has bright shiny yellow flowers in open clusters on 9-18 inch stems and blooms in late spring.
For more information on bulbs, see the following Colorado State University Extension Fact Sheet