We have found 22 plants that meet your criteria.

Price Pruned
Granny's Bonnet ‘Aquilegia vulgaris var. stellata Black Barlow’ Striking dark purple, double flowers NOW £4.99 Buy
Crocus Special Offers
Day Lily ‘Hemerocallis American Revolution’ Large, deep blood-red flowers in summer NOW £5.99 Buy
Intermediate Bearded Iris ‘Iris Langport Flame’ Sumptuous purple and orange fragrant flowers £6.99 Buy
Tree Peony / Tree Paeony... ‘Paeonia delavayi’ Tree peony with deep, maroon flowers £16.99 Buy
Pincushion Flower ‘Scabiosa atropurpurea Chile Black’ Deep claret, almost black flowers £5.99 Buy
Moor Grass ‘Sesleria autumnalis’ Perfect for informal edging £5.99 Buy
Double Late Tulip ‘Tulipa Black Hero’ Almost black double flowers £5.00 Buy
Tulip Black Jewel ‘Tulipa Black Jewel’ A tall, very dark coloured tulip £7.50 Buy
Fringed Tulip ‘Tulipa Curley Sue’ Delicately fringed flower petals £4.00 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
African Lily ‘Agapanthus Black Pantha’ Deep blue, almost black flowers £8.99 Buy
Granny's Bonnet ‘Aquilegia vulgaris William Guinness’ Unusual purple-black flowers £5.49 Buy
Amaryllis Black Pearl ‘Hippeastrum Black Pearl’ Stunning dark maroon flowers £8.99 Buy
Siberian Iris ‘Iris chrysographes black-flowered’ Stunning, almost black flowers. For a damp spot £6.99 Buy
Price Pruned
Beard Tongue ‘Penstemon Raven’ Dramatic, deep purple, foxglove-like flowers NOW £5.49 Buy
Black-eyed Susan ‘Rudbeckia occidentalis Green Wizard’ Bright green sepals with black centres £5.99 Buy
Black Elder (syn. Black Beauty)... ‘Sambucus nigra Gerda’ Dramatic purple foliage £8.99 Buy
Parrot Tulip ‘Tulipa Black Parrot’ Dramatic, blackish-purple, cup-shaped flowers £5.00 Buy