Now is the best time to plant these stars of spring and early summer.
Alliums, or ornamental onions have come a long way since the deservedly popular variety ‘Purple Sensation’ became the darling of garden designers and gardeners.
Recent breeding has brought a swathe of new varieties large and small, which now take their place alongside firm favourites which have stood the test of time. The result is a rich and astonishing diversity of bloom that brings a little floral pizzazz to early summer borders and beyond. Most also perform equally well in potted displays, ideal if you don’t have space for the larger types.
Ornamental onions will grow in most well-drained soils as long as they are not constantly wet or droughted when in active growth in spring. Planting them now enables them to produce roots and become established before flowering. They prefer full sun, successively dwindling away in gloomier conditions, or if swamped by expanding perennials. Plant bulbs as deep as they are high, especially important with the larger flowered types to ensure they are well anchored. Choose an open patch among perennials to enable the leaves to emerge and expand.
Species vary with respect to how long the foliage persists, some withering away before the flowers mature, others such as A. karataviense lasting much longer, adding the display. Alternatively, smaller varieties can be started in pots, planted out in late winter. You will need to control slugs and snails as they soon tatter the leaves, and also annoyingly strip flower stems so the blooms fail or collapse.
The bulbs of many larger varieties also split after flowering, so the display in the second year is often smaller until they build up strength again, or you continue to replant fresh stock.