We have found 161 plants that meet your criteria.

hyssop
Agastache 'Black Adder' hyssop Distinctive violet, bottlebrush flowers £7.49 Buy
hollyhock
Alcea rosea 'Nigra' hollyhock Tall stems bearing near-black flowers £1.49 Buy
New
ornamental onion
Allium atropurpureum ornamental onion A smashing new introduction £7.99 Buy
star of Persia
Allium cristophii star of Persia Huge globes of star-like, lilac flowers £8.99 Buy
allium
Allium hollandicum 'Purple Sensation' allium Rich, deep purple globes £8.99 Buy
chives
Allium schoenoprasum chives Edible leaves and button-like flowers £5.99 Buy
ornamental onion
Allium schubertii ornamental onion Giant pink starbursts £8.99 Buy
round-headed leek
Allium sphaerocephalon round-headed leek Small, wine-coloured flowers on tall stems £8.99 Buy
ornamental onion
Allium 'Globemaster' ornamental onion Enormous, deep violet globes £8.99 Buy
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
New England Aster
Aster novae-angliae 'Violetta' New England Aster Beautiful deep purple flowers £7.99 Buy
michalmas daisy
Aster pyrenaeus 'Lutetia' michalmas daisy One of the most reliable asters £7.99 Buy
masterwort
Astrantia major 'Rubra' masterwort Gorgeous plum-coloured flowers £7.99 Buy
false indigo
Baptisia australis false indigo Decorative seed-pods in winter £7.99 Buy
dalmatian bellflower
Campanula portenschlagiana dalmatian bellflower Vigorous and low-growing £6.99 Buy
New
herbaceous clematis (group 3)
Clematis 'Fleuri' herbaceous clematis (group 3) A compact grower - ideal for a pot £14.99 Buy
clematis (group 3)
Clematis 'Lord Herschell' clematis (group 3) A compact perennial form £9.99 Buy
delphinium
Delphinium 'Black Knight Group' delphinium Spikes of dark purple flowers with black centres £7.99 Buy
pink
Dianthus amurensis pink A mat-forming pink with mauve flowers £6.99 Buy