They bloom from late spring to early summer. Alliums grow best in full sun. The solitary heads are borne atop a 3 to 4 foot tall stem. The giant onion usually blooms in late June. Lily leeks grow 8 to 12 inches tall and are best utilized in borders and rock gardens.
Flowers are star-shaped, bright blue with white centers.
The 6-inch plants prefer sunny sites. There are also white and pink flowered varieties of this species. Flower colors include yellow, blue, lavender, and purple. Many blossoms are striped. Plant crocuses in groups of a dozen or more of the same color for maximum effect.