We have found 10 plants that meet your criteria.

granny's bonnet
Aquilegia vulgaris var.stellata 'Black Barlow' (Barlow Series) granny's bonnet Striking dark purple, double flowers £7.49 Buy
granny's bonnet
Aquilegia vulgaris 'William Guinness' granny's bonnet Unusual purple-black flowers £7.49 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
lily
Lilium 'Dimension' lily Brooding and sumptuous colour £5.99 Buy
New
lily bulbs
Lilium 'Sixth Sense' lily bulbs Brooding colour for the summer border £2.99 Buy
black elder (syn. Black Beauty)
Sambucus nigra f. porphyrophylla 'Gerda' (PBR) black elder (syn. Black Beauty)... Dramatic purple foliage £10.99 Buy
red hook sedge
Uncinia rubra red hook sedge Wonderful deep bronzy-red foliage £7.99 Buy
daylily
Hemerocallis 'American Revolution' daylily Large, deep blood-red flowers in summer £8.49 coming soon
Price Pruned
tree peony / tree paeony
Paeonia delavayi tree peony / tree paeony... Tree peony with deep, maroon flowers NOW £19.99 coming soon