We have found 26 plants that meet your criteria.

Allium Purple Sensation ‘Allium hollandicum Purple Sensation’ Rich, deep purple globes £3.50 Buy
Allium cristophii ‘Allium cristophii’ Huge globes of star-like, lilac flowers £5.00 Buy
Allium Globemaster ‘Allium Globemaster’ Enormous, deep violet globes £5.00 Buy
Allium Schubertii ‘Allium schubertii’ The flowers look like giant fireworks £7.50 Buy
Round-headed Leek ‘Allium Sphaerocephalon’ Small, wine-coloured flowers on tall stems £4.00 Buy
Single Late Tulip ‘Tulipa Andre Rieu’ One of the last tulips to flower £4.00 Buy
Triumph Tulip ‘Tulipa Arabian Mystery’ Sumptuous bi-coloured blooms £5.00 Buy
Lily-flowered Tulip ‘Tulipa Ballade’ Listed by the RHS as one of their top 10 tulips £4.00 Buy
Double Late Tulip ‘Tulipa Black Hero’ Almost black double flowers £5.00 Buy
Fringed Tulip ‘Tulipa Blue Heron’ Long-lasting fringed flowers £4.00 Buy
Parrot Tulip ‘Tulipa Blue Parrot’ Luscious lavender-mauve petals £5.00 Buy
Triumph Tulip ‘Tulipa Blue Ribbon’ Long lasting cut flowers £4.00 Buy
Lily-flowered Tulip ‘Tulipa Burgundy’ Richly coloured lily-shaped flowers £4.50 Buy
Single Late Tulip ‘Tulipa Caravelle’ Perfect for adding height to bedding displays £4.00 Buy
Fringed Tulip ‘Tulipa Curley Sue’ Delicately fringed flower petals £4.00 Buy
Double Late Tulip ‘Tulipa Lilac Perfection’ Flowers grow into generous lilac globes £5.00 Buy
Lily-flowered Tulip ‘Tulipa Maytime’ A tough tulip for bedding displays or pots £3.50 Buy
Triumph Tulip ‘Tulipa Negrita’ A sturdy tulip with rich colour £3.00 Buy
Single Late Tulip ‘Tulipa Paul Scherer’ Possibly the darkest purple tulip £4.00 Buy
Single Late Tulip ‘Tulipa Queen of Night’ Velvety, dark maroon blooms £3.00 Buy