We have found 46 plants that meet your criteria.

African lily
Agapanthus 'Black Pantha' (PBR) African lily Deep blue, almost black flowers £11.99 Buy
hollyhock
Alcea rosea 'Nigra' hollyhock Tall stems bearing near-black flowers £1.49 Buy
granny's bonnet
Aquilegia vulgaris 'William Guinness' granny's bonnet Unusual purple-black flowers £7.49 Buy
granny's bonnet
Aquilegia vulgaris var.stellata 'Black Barlow' (Barlow Series) granny's bonnet Striking dark purple, double flowers £7.49 Buy
clematis (group 3)
Clematis 'Black Prince' clematis (group 3) Beautiful deep purple flowers £12.99 Buy
clematis (group 3)
Clematis 'Warszawska Nike' clematis (group 3) Sumptuous deep purple flowers, £9.99 Buy
dahlia bulbs
Dahlia 'Karma Choc' ® dahlia bulbs Opulent chocolate-scented flowers £3.99 Buy
dusky cranesbill
Geranium phaeum dusky cranesbill Small, deep maroon flowers. Good for groundcover £7.49 Buy
dusky cranesbill
Geranium phaeum var. phaeum 'Samobor' dusky cranesbill Small, purple-black flowers. Good for damp... £7.49 Buy
Price Pruned
Lenten Rose hellebore
Helleborus × hybridus 'Harvington Double Lime' Lenten Rose hellebore A gorgeous, new variety NOW £11.99 Buy
Price Pruned
Lenten Rose hellebore
Helleborus × hybridus Harvington double purple Lenten Rose hellebore Stunning double flowers NOW £11.99 Buy
Price Pruned
Lenten Rose hellebore
Helleborus × hybridus 'Harvington Shades of the Night' Lenten Rose hellebore Early spring flowers in... NOW £9.99 Buy
Price Pruned
Lenten Rose hellebore
Helleborus × hybridus Harvington Smokey Blues Lenten Rose hellebore Unusual, dark purple flowers... NOW £12.99 Buy
daylily
Hemerocallis 'American Revolution' daylily Large, deep blood-red flowers in summer £8.49 coming soon
amaryllis Black Pearl bulb
Hippeastrum 'Black Pearl' amaryllis Black Pearl bulb Stunning dark maroon flowers £7.99 coming soon
New
hyacinth
Hyacinthus 'Dark Dimension' hyacinth Darkly delicious £3.99 coming soon
bearded iris
Iris 'Superstition' bearded iris Purple-black flowers £8.99 Buy
Siberian iris
Iris chrysographes black-flowered Siberian iris Stunning, almost black flowers. For a damp spot £8.99 Buy
New
spencer sweet pea Beaujolais
Lathyrus odoratus 'Beaujolais' spencer sweet pea Beaujolais One of the darkest forms £6.99 coming soon
spencer sweet pea seed Beaujolais
Lathyrus odoratus 'Beaujolais' spencer sweet pea seed Beaujolais... One of the darkest forms £1.89 Buy