1/3/5/10/15/20 Allium Purple Sensation Bulbs Generously 10/12 cm (circumference) bulbs for your autumn gardening Masses of deep violet-purple florets pack impressive rounded flower heads up to 10cm across. Flowers in May. Height 100cm. Bulb size 10/12cm. The tall flowers of 'Purple Sensation' appear in summer, showing off rounded heads full of deep violet flowers. These alliums are perfect for a sunny border. These hardy perennial 'ornamental onions', which explode into bloom in early summer, are becoming ever more popular for creating dramatic border displays, and for cutting. And even when the initial display is over the dried heads look amazing in the garden or in a vase indoors.