Allium

With a flowering period from late spring into summer (for many of the species and cultivars) the ornamental onion is ubiquitous at RHS Chelsea. With good reason, as they add a different dynamic to a border, with their rounded heads hovering above other plants, either dotted through, or creating a naturalistic looking drift. Lower growing forms can be suited to a rock garden, or to flower before a neighbouring companion produces too much growth. Taller forms are good growing through purple sage  (Salvia officinalis 'Purpurascens') or growing behind Hylotelephium for example, as a good way of hiding the deteriorating foliage. Either way an essential component to a sunny border.

The flowers of all onion species are highly attractive to insects, especially bumblebees, honeybees and hoverflies. The seeds of most species have an oil-body that attracts ants: the ants take the oil-body as food, dispersing the seed in the process. Some species (especially A. triquetrum and A. paradoxum, neither of which we supply) are increasing, aggressive invaders of natural habitats, especially in the warmer south and southwesterly parts of the country: these should never be allowed outside the confines of gardens.

Allium now includes the old genus Nectaroscordum.