Blooming Season for Giant Allium

Blooms

• Since the early 1800s, giant allium has been cultivated for its purple flowers. As the earliest days of summer approach, the large, each round flower head makes its appearance atop a thick, leafless stem reaching 3 to 5 feet in height. Composed of small, star-shaped flowers, each held on its own tiny stalk, every dense flower head measures 4 to 6 inches in diameter. The flower heads mature from deep purple to soft lavender and are favored by butterflies and hummingbirds. The flowers are long-lasting when cut but also become what are considered attractive seed heads when left to dry on their stems in the garden.

Placement

• Proper placement of giant allium is important for enjoying its blooms. Because of the plant's height and size of its blooms, balance is achieved best by putting the plant toward the back of a border. At peak flowering, the rosette of foliage at each stem's base is already preparing for dormancy and yellowing. This drawback is easily overcome by pairing giant allium with a large-leaved companion to camouflage the fading leaves. Staking your plant for added support may be necessary. A sheltered spot near the back of the border won't diminish giant allium's dramatic impact, but it will protect the heavy flower heads from wind that could snap its stems.

Planting Considerations

• Like the common onion, giant allium grows from a bulb. If you want springtime blooms, plant giant allium bulbs in fall in a site with well-drained soil and full-sun exposure. Soil drainage is very important because giant allium's bulbs, measuring 2 to 3 inches across, can be prone to rot if kept too wet. Maximize the blooms' impact by planting your giant allium in groups of five to seven bulbs, and give them plenty of room to grow. As a general guide, plant each bulb at a depth two to three times the bulb's diameter with one bulb per square foot. The plants reach their mature size in two to five years.

Care

• Giant allium's blooms occur with very little effort. Relatively carefree for a gardener, it's simple to grow and bothered by few pests. Although its leaves and stems emit the aroma of onion when cut, giant allium has no culinary value -- not even to deer and rodents. Hardy in U.S. Department of Agriculture plant hardiness zones 5 through 9, it can do well in colder zones with added winter protection. When mature giant allium plants decrease their flower production, its time for an increase in your garden. In fall, gently dig and lift the bulbs and the offsets you find around them. Then divide the bulbs and offsets, and replant them to add more of the flowering plants to your garden.