When to Plant Allium Bulbs

Allium (Allium spp.), commonly known as "ornamental onion” or "flowering onion," is a relative of edible onions (Allium cepta, U.S. Department of Agriculture plant hardiness zones 5 through 10), garlic (Allium sativum, USDA zones 3 through 9) and chives (Allium schoenoprasum, USDA zones 5 through 11). With approximately 500 different species in this genus, plant hardiness ranges widely over USDA zones 3 through 9. In the spring, it produces thin onion-like stems that grow from 8 inches to over several feet tall. The rounded heads of the flowers are reminiscent of pictures found in a Dr. Seuss book, with globe-like clusters in shades of rose, yellow, white or mauve.

1. Planting bulbs

   • The timing to plant allium bulbs is in the fall, when the leaves of deciduous trees are falling. In some areas this will be September, while in others, it will be October. The bulbs will remain dormant until cold weather has passed, then sprout and bloom.

   Dividing clumps

   • Thick clumps of established allium may be lifted, divided and replanted in the early spring before the growing season begins.