Allium Mix Upright stems add a strong vertical accent to cottage garden borders. These magnificent allium bulbs produce an explosion of colour, followed by architectural seedheads that create a spectacular autumn display. Undemanding and easy to grow, these magnificent allium flowers are also excellent for cutting. Allium hollandicum - Dense globes of mauve-purple flowers measuring up to 10cm (4) across in early summer. Height: 90cm (35). Spread: 10cm (4). Allium sphaerocephalon- An understated allium with unusual oval shaped, purple green flower heads, that associates beautifully with swaying grasses. Height: 50cm to 1 metre (20 to 40). Spread: 8cm (3)./li> Allium caeruleum - Bright blue globes of starry flowers are carried on stiff upright stems. Height: 60cm (24). Spread: 8cm (3). Allium \'Purple Sensation\' - Globes of starry purple flowers that measure up to 8cm (3) across. Height: 90cm (36). Spread: 10cm (4).