We have found 16 plants that meet your criteria.

Agapanthus 'Black Pantha' African Lily Deep blue, almost black flowers £8.80 Buy
Aquilegia vulgaris 'William Guinness' Granny's Bonnet Unusual purple-black flowers £5.37 Buy
Price Pruned
Aquilegia vulgaris var. 'stellata Black Barlow' Granny's Bonnet Striking dark purple, double flowers NOW £5.37 Buy
Geranium phaeum Dusky Cranesbill Small, deep maroon flowers. Good for groundcover £5.86 Buy
Price Pruned
Geranium phaeum var. 'phaeum Samobor' Dusky Cranesbill Small, purple-black flowers. Good for damp... NOW £5.37 Buy
Crocus Special Offers
Helleborus x hybridus 'Harvington Shades of Night' Lenten Rose Early spring flowers in... NOW £7.82 Buy
Crocus Special Offers
Helleborus x hybridus 'Harvington Smokey Blue' Harvington Hellebore Unusual, dark purple flowers with a deep... NOW £8.80 Buy
Hemerocallis 'American Revolution' Day Lily Large, deep blood-red flowers in summer £5.86 Buy
Iris 'chrysographes black-flowered' Siberian Iris Stunning, almost black flowers. For a damp spot £6.84 Buy
Iris 'Langport Flame' Intermediate Bearded Iris Sumptuous purple and orange fragrant flowers £6.84 Buy
Price Pruned
Iris 'Superstition' Bearded Iris Purple-black flowers NOW £5.86 Buy
Iris chrysographes Siberian Iris Deep purple flowers. Gorgeous beside water £6.84 Buy
Rudbeckia occidentalis 'Green Wizard' Black-eyed Susan Bright green sepals with black centres £5.86 Buy
Scabiosa atropurpurea 'Ace of Spades' Pincushion Flower Gently fragrant they make good cut flowers £5.86 Buy
Scabiosa atropurpurea 'Chile Black' Pincushion Flower Deep claret, almost black flowers £5.86 Buy
Sesleria autumnalis Moor Grass Perfect for informal edging £5.86 Buy