Care-free bulbs: Gorgeous ornamental onion

If you think of onions as bulbs that make you weep, think again. Ornamental onions have but a faint onion scent and only when the leaves get crushed. What they offer instead are beautiful flowers in shades of purple, lavender, mauve, and white.

Individual flowers are clustered together atop sturdy stems, and they open in unison to create an impressive globe or an open starburst.

Ornamental onions make great accent plants in the perennial border from late spring to summer, when most reach their pinnacle of beauty. And the flowers, both fresh and dried, are good for gorgeous bouquets that offer year-round enjoyment.

1. Plant allium bulbs in the fall in a sunny site with good drainage, otherwise the bulbs may rot.
2. Dig a hole about 12 centimetres (five inches) deep for small bulbs, such as those of 'Purple Sensation', and 20 centimetres (eight inches) deep for larger bulbs.
3. Set bulbs in soil with the pointed ends up, in groupings of three to five for the smaller alliums or individually for the larger ones.

Unique benefits

• Ornamental onions produce sulphur, the source of the characteristic onion scent, which naturally repels insect and four-footed pests: a desirable benefit.
• In fact, growing any member of the onion family near plants that usually attract pests can offer protection to the companions.

Points to consider

• Alliums do not multiply quickly from bulbs, but some reseed.
• Seedlings look like grass and take several years to flower.
• If you don't want an abundance, cut off and dispose of old flowers as they fade to keep them from setting seed. Better yet, cut the flowers as they open for a bouquet and enjoy.

One of the easiest ornamental onions to grow is Allium hollandicu. Also known as the 'Purple Sensation'.

• The one metre (three foot) tall plant produces a dense, 10 centimetres (four inches) wide cluster of rich violet flowers.
• Because the leaves are skimpy, consider combining it with a full-foliaged bedfellow, such as yarrow or zinnia.
• With its 15 to 25 centimetre (six to ten inch) flower clusters on 30-centimetre-tall to 60-centimetre-tall (12-inch-tall to 25-inch-tall) stems, the star of Persia (A. christophi.) is suitable for the front of the border. Purple flowers with a silvery metallic sheen appear in late spring.

Another big-flowered species is giant onion (A. giganteu.), which has dense, 15 centimetre (six inch) purple clusters atop stems that can reach 1.2 metres (four feet).

Most ornamental onions have plain grassy foliage, but A. karataviens. has wide, arching, lightly pleated blue-green leaves. Its mauve-pink flowers blend with everything from silver-leaved artemisia to hardy geraniums.

Stems grow to about 20 centimetres (eight inches) tall, topped by eight-centimetre-wide (three-inch-wide) flower clusters.

A. senescen. also has attractive foliage. The grey-green leaves are loosely twisted and grow in a whorled clump, from which 60-centimetre-tall (25-inch-tall) stems of mauve flowers emerge in late summer.

Another easy-to-grow allium, drumstick allium (A. sphaerocephalu.), produces its 5-centimetre-wide (two-inch-wide) oblong clusters of reddish-purple flowers on one-metre-tall (three-foot-tall) stems that sway in the breeze in early summer.

These easy-to-maintain blossoms are a colourful addition with benefits most gardeners appreciate. Add them to your garden and enjoy all that they have to offer.