Allium Giganteum Ornamental Onion Bulb

Plant Allium Giganteum ornamental onion bulbs before the first frost in fall, and in late spring to early summer the following year, they bloom in softball-sized—5- to 6-inch—spheres dense with clusters of tiny star-shaped lilac-purple florets atop a thick scape rising above a basal rosette of greyish-green, strap-shaped leaves. Among the largest and tallest alliums available, Giganteum alliums grow to a mature size of 34 to 36 inches tall. The blooms are nectar rich, so they beckon to bees, butterflies, beneficial insects, and other pollinators; once the flower heads go to seed, they afford extra-long-lasting displays in the garden. But they also make spectacular cut flowers, fresh or dried.

An Allium giganteum species, commonly called ornamental onion or giant onion, Giganteum is a bulbous perennial with an upright habit and is one of the tallest of the ornamental onions. Alliums belong to the same family as garlic, onions, chives, and shallots; but ornamental alliums have beautiful blooms with interesting shapes, colors, and textures. Giganteum is a dramatic background plant for mixed borders and garden beds, but they also put on quite a show in a layered lasagna planting with grape hyacinths and anemones in deep patio pots.

Ornamental onions are super easy to grow and maintain. Site bulbs in a sunny, sheltered location with average, medium moist, freely draining soil. Although alliums are not picky about soil types, soggy soils will cause bulbs to rot. Plant Giganteum allium bulbs 9 to 12 inches apart and 5 to 6 inches deep and water well to settle bulbs. Once growth begins in spring, fertilize the bulbs with organic bulb food. If flower production decreases over time, dig, divide, and replant the bulbs. Deer and rodents are not attracted to ornamental onions.

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