Allium Giganteum Ornamental Onion Bulb

Plant Allium Giganteum ornamental onion bulbs in the fall before the first frost, and by late spring to early summer the following year, your garden will be graced with spectacular softball-sized, 5- to 6-inch spherical blooms. These dense clusters of tiny star-shaped lilac-purple florets sit atop thick scapes that rise above a basal rosette of greyish-green, strap-shaped leaves. As one of the largest and tallest alliums available, Giganteum alliums reach an impressive height of 34 to 36 inches at maturity. The nectar-rich blooms are a magnet for bees, butterflies, and other beneficial pollinators. Even after the flowers fade, the seed heads provide long-lasting interest in the garden, and they make spectacular cut flowers, whether fresh or dried.

Giganteum, a species of Allium giganteum, commonly known as ornamental onion or giant onion, is a bulbous perennial with an upright habit. While related to garlic, onions, chives, and shallots, Giganteum alliums are prized for their striking blooms that add unique shapes, colors, and textures to your garden. These alliums serve as dramatic background plants for mixed borders and garden beds, and they create a stunning show in layered lasagna plantings with grape hyacinths and anemones in deep patio pots.

Ornamental onions like Giganteum are incredibly easy to grow and maintain. For best results, site the bulbs in a sunny, sheltered location with average, medium moist, well-draining soil. While alliums are adaptable to various soil types, avoid soggy conditions, as this can cause the bulbs to rot. Plant Giganteum allium bulbs 9 to 12 inches apart and 5 to 6 inches deep, then water well to settle them. As growth begins in the spring, fertilize the bulbs with organic bulb food to encourage robust flowering. If flower production decreases over time, dig up the bulbs, divide them, and replant to rejuvenate the display. Ornamental onions are also deer and rodent resistant, making them a resilient and low-maintenance choice for your garden.

For tips on creating a stunning spring bulb garden, check out our blog post on How to Plant a Spring Bulb Garden. And don't forget to visit our Garden Essentials page for all the tools and products you'll need to get started.