Alluring alliums

Alliums can be big, bold, purple-headed statements in a late-spring garden, yet they are simply ornamental onions. Anne Swithinbank selects the best varieties

- Anne Swithinbank

DRUMSTICKS, fireworks, exclamation marks and cricket balls are just some of the words used to describe ornamental onions. Cousins of the leek, onion, garlic and chive, these showy plants grow from bulbs planted now in autumn to bloom mainly in May and June next year just as tulips come to an end. Best known is probably ‘Purple Sensation’, an older cultivar cheap to buy and happy to naturalise itself, threading borders with 3ft (1m)-tall stems of purple globes. If you want to avoid self-seeding, deadhead or buy more expensive sterile cultivars that last in flower for longer, usually around six weeks.

The many species of allium originate from Central Asia and the Middle East, where growth starts as the snows melt and rising temperatures encourage flowerbuds to open so they can seed before everything dies back to survive hot, dry summers. In gardens, spring foliage tends to turn yellow just as the flower stem elongates, and this can be easily masked by setting the bulbs informally between other plants.

For reliably perennial alliums capable of flowering every year with little input, choose those given the RHS Award of Garden Merit (AGM). Others will flower spectacularly in their first year, the globe size might diminish in the second and thereafter all you’ll see is leaves. Should this happen, lift the bulbs after flowering (they have usually multiplied), dry and store until autumn, and then replant in good, deep well-draining soil.

Plenty of variation