They don't just taste good. Ornamental onions can look great too, and none more so than the great purple allium, writes Jane Powers
Well, irises were certainly being touted as the floral stars of last month's Chelsea Flower Show, but the plants that moved me were the onions. I'm talking about the ornamental kinds, and in particular, the excellent Allium hollandicum 'Purple Sensation'. Groups of it featured in several of the gardens, bouncing over the other perennials like scatterings of purple tennis balls.
Its cheerful spheres - and those of its more beefy brothers 'Globemaster' and 'Gladiator' - are one of the jauntiest ways of bringing some colour to the early summer border. You can't be in a bad mood around a bunch of alliums. These tall drumstick onions look most effective rising out from other plants. A. christophii, however, is shorter (about 40-50cm), and needs a position at the front of a border, where you can admire its mauvish, metallic, starry footballs.
A. schubertii is another front-liner. It has pale purple inflorescences with little florets shooting out on stalks at different lengths, like a floral firework. Also deserving of a place where you can study it closely is A. karataviense. This Turkish native has uncharacteristically large leaves, which arch out from the base like flat, lolling tongues. The spherical flower heads are a creamy, faded-rose kind of colour, like that of old-fashioned, expensive, silk underwear. A clearer-looking variety is the cultivar Ivory Queen.
For the horticutural fashionistas who must have the latest of everything, a new cultivar (launched at last year's Chelsea Flower Show) is 'Silver Spring', available by mail order from both Avon Bulbs and Broadleigh Gardens in Britain (www.avonbulbs.com; www.broadleighbulbs.co.uk). Unusually for an onion, it is reputed to be sweet-scented. I saw one recently, but wasn't able to manoeuvre my nose in close enough to examine its fragrance. A tall allium (up to a metre), it has white florets with dark-red ovaries, which look like a dabs of blackberry jam. As the plant matures, the entire flower head becomes suffused with pink.
Blooms that change dramatically during their flowering cycle are more engaging than those that just open up and sit around until they die. A plant that used to be an allium, but which has been shifted to another genus, is Nectaroscordum siculum subsp. bulgaricum (and I'm afraid it has no common name). The little individual lampshade flowers (white, flushed with green and wine) are carried on mobile tentacles. They arch gracefully downwards when first open, and over the course of a few days gradually hoist themselves up vertically, to fade, dry and disperse their seeds.
As I mentioned, this southeastern European has been cast out of the alliums, but it has many of that clan's features, including the oniony-smelling flesh, and - more attractively - long-lasting seedheads. When you get tired of your dead onions in the garden, bring them into the house for a bit of geometrically-pleasing interior decoration. And that goes for edible onions and leeks too, if you've let them get away on you in the veg patch (where their big drumsticks of flower are delightful, and a magnet for bees). They also produce excellent dried globes.
Alliums are classic May and June plants, when the show-off 'Purple Sensation' and its ilk are doing their thing. But their season starts earlier and goes on later than this. Early April brings the wild garlics: the native ramsons (A. ursinum) with its flat leaves and starry white flowers; and the three-cornered garlic (A. triquetrum), which was introduced from the western Mediterranean more than 200 years ago. It looks like an albino bluebell, with triangular stems, and is very pretty.
But don't be tempted to bring either of these wildlings into the domestic garden, unless you have plenty of space. Both look lovely at the edges of woodlands or under hedgerows. Don't offer them anything more deluxe. They will overrun your best borders if you give them a toehold.
At the latter end of the season, in July and August, there are some smaller-headed, more discreet onions. A. sphaerocephalon has grape-sized, deep-red bobbles on tall stalks (50-60cm), which look good dotted through naturalistic plantings of perennials and airy, ornamental grasses. The yellow A. flavum is shorter, and appears around the same time, as does the pink-flowered A. cernuum, one of the few north American alliums in cultivation (most are from Europe and Asia). Possibly the last to flower is Chinese or garlic chives (A. tuberosum) with its small white umbrellas that last into September.
Alliums are bulbs, so they don't like to be sitting in too much moisture when they are dormant (from summer onwards). Plant them in autumn in well-drained soil in a sunny position - and look forward to having your sprits elevated by their happy, bouncy orbs.
Diary dates
Sunday, June 18th, 10am-8pm: Jennings Family Garden annual open day at Cashel Beg, Enniskeane, Co Cork. All proceeds to Aid Cancer Treatment (Act), Cork University Hospital. Home baking, tea, coffee. Voluntary contributions.
Gardeners who are not able to give up an entire week for the International Clematis Society Conference (June 30th-July 7th) at DCU, may attend the event on July 3rd or 4th (€150 for either day, €200 for both). For details: 01-2802641; www.clematis2006.com