Dahlia Black Jack

Dahlia ‘Black Jack’ is a striking cactus dahlia known for its exceptionally dark colouring and strong architectural form. The blooms are made up of narrow, pointed petals that are slightly twisted, creating a spiky, starburst-like shape that stands apart from more rounded decorative dahlias. The colour is rich and intense, ranging from deep burgundy to near-black in shaded light, with flashes of dark crimson and velvety red becoming visible as the flowers open and catch the sun. This shifting depth gives each bloom a sense of movement and richness rather than a flat dark tone. 

Flowers measure approximately 12 to 15 cm across and are held on long, sturdy stems that rise well above the foliage. Plants grow to around 90 to 120 cm tall, forming a strong, upright habit suited to borders and cutting gardens.  Dahlia ‘Black Jack’ flowers continuously from midsummer until the first frosts when regularly deadheaded. Its darker tones create strong contrast in planting schemes, pairing especially well with soft pinks, creams, pale apricots, silver foliage, ornamental grasses, and deeper jewel-toned combinations. 

As a cut flower, it is highly valued for its structure and impact. The spiky form adds definition in arrangements, working as a focal or contrast bloom alongside softer shapes. Best grown in full sun in fertile, well-drained soil, with staking recommended early in the season to support its height and flower weight.