Allium has no less then 500 species, each prettier or more unusual in shape then the last. Also known as ornamental onions, allium is ideal for making colour and height combinations in the border.
Most ornamental onions flower in June, just after the real spring flowerers, and before most summer flowers comes into bloom. They therefore form an indispensable perennial that keeps the border in flower well into the year.
For best results, plant your allium bulbs in November in a sunny spot, quite deep (just over twice as deep as the height of the bulb), in well-drained fertile soil. Because of the great variety of bulb sizes (from 3cm to over 20cm), it is best to draw up a planting plan. You can then keep track of their location and heights in the border, and also make allowances for the fact that alliums foliage dies back quite early. By planting them in combination with plants like Stork’s Bill, for example, you can cover the gaps made by dying foliage.
Nearly all have narrow, basal leaves smelling of onions when crushed, and most have small flowers packed together in a dense, spherical or shuttlecock shaped umbel. Dried umbels of tall border species are good for winter decoration.
Borne on sturdy stems that emerge from between grayish-green leaves, Allium ‘Gladiator’ grows well and makes a great combination between tall border plants like phlox, speedwell, yarrow, knotweed (Persicaria), the off-white gypsophila or the blue strawflower (Catanache Caerulea) (both about 50 cm).
The delicate Blue Globe Onion (Allium Caeruleum) works well between the lower border plants and the unusual, low growing and highly decorative Allium Karataviense ‘Ivory Queen’® deserves a prominent spot, at the front of the border,  and is also ideal for pots and planters.
Chives are a fantastic type of ornamental onion to bring variety and height difference in your border. Unlike other alliums, chives keep on producing new foliage, and the little additional extra is that the stalk-like foliage is edible. It is most tasty before the plant flowers. It is a very tasty addition to boiled or fried eggs, tomato, on salads or in soups.
Alliums are available in a wealth of varieties, colours and sizes:
Allium Amplectens has magnificent white globular flowers on tall stems. The tips of the petals are a pale lavender.
Allium ‘Fireworks’ have pendulous flowers in yellow, purple and white which is a most striking feature of this allium variety. The shape of the flowers suggests an exploding firework.
Allium ‘Forelock’ is a delightfully fragrant ornamental onion with a distinctive ‘forelock’ on each flower. The flowers which can grow to 20 cm across gradually open from the top to the bottom. This variety is an excellent garden subject, beautiful in a vase and also suitable for dried flower arrangements.
Allium ‘Gladiator’ produces magnificent light-purple, globe-shaped flower heads that are larger than tennis balls. Enrich your spring garden with this exceptionally striking plant. The large flowers are 15-20 cm across and make fantastic, long-lasting cut-flowers. These ornamental onions are increasingly popular, deserving prominence in both traditional and contemporary gardens.
Allium Karataviense ‘Ivory Queen’® (pictured top right) is an ornamental onion and is also known as Turkestan onion. Both the flowers and the foliage are striking. The leaves are silvery-green with pale veins, and the handsome globular flowers are a pinkish-white to cream. Attractive to butterflies and bees.
Alliums are fully to frost hardy. They should be planted during the autumn in an open, sunny position in well drained soil. They are best left undisturbed to form clumps. If the flowers become smaller after a few years, split and replant to allow more space.