How to Grow Ornamental Allium (Flowering Onion)

How to Grow Ornamental Allium (Flowering Onion)

Perennial

There are several hundred allium species—all members of the onion family. Well-known alliums include chives, onions, garlic, and shallots. For flower gardeners, ornamental alliums (flowering onions) offer a wide variety of colors, heights, and bloom times.

These hardy, easy-to-grow flowering bulbs produce big, multi-floreted, round blooms atop tall, sturdy spikes. Generally blooming late spring to early summer, they return for many years with little attention once established.

As ornamentals, the largest giant varieties (Allium giganteum) are most sought after.

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Plant Propagation

Ornamental alliums are grown from bulbs. The flower head also produces seeds, but most gardeners plant the easy-to-handle bulbs.

Plant bulbs in spring as soon as the ground can be worked, at a depth of twice the bulb's diameter.

If planting seeds, sow directly into the garden just ⅛ inch deep.

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How to Grow Ornamental Allium Plants

Growing ornamental alliums is very easy. They like full sun to partial shade. They tolerate poor soils but prefer good drainage. A general-purpose fertilizer in early spring gives them a seasonal boost.

Once established, they grow well with few problems. Keep soil moist to slightly dry. Water during dry periods once or twice weekly. Keep well-weeded or apply 2–3 inches of mulch for a tidy appearance.

Alliums return yearly for many years.

Did You Know? Alliums make good cut flowers but give off a slight onion scent—no surprise there!

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Insect and Disease

Alliums have few insect or disease problems.

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