loading

Dahlia 'Black Jack'

semi-cactus (dinnerplate) dahlia

Product Image
This fabulous, show-stopping, semi-cactus variety Dahlia produces dark purple, dinner-plate sized blooms that are near black in appearance. Contrasting with mid-green foliage, ‘Black Jack’ is a superb addition to any garden border, patio pot display, or a sumptuous choice for a cut flower vase.

How to care for Dahlia Black Jack:

Dahlia tubers can be planted outside after frost, or started off in pots under glass in late winter to early spring. Plant them horizontally approximately 12cm deep, making sure the ‘eyes’ are uppermost. Allow enough room between each tuber so the plants can grow and spread to their full size without being overcrowded. While in growth, provide a high-nitrogen liquid feed each week in June, then a high-potash fertiliser each week from July to September. Stake with canes or brushwood if it becomes necessary. In mild areas, leave them in situ over winter, but protect the crown with a generous layer of dry mulch. In colder areas, carefully lift and clean the tubers once the first frosts have blackened the foliage and allow them to dry naturally indoors. Then place the dry tubers in a shallow tray, just covered with slightly moist potting compost, sand or vermiculite and store in a frost-free place until planting out again.
Flowering period:
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
Eventual height:
1.4m
Eventual spread:
1.2m
Position:

Full sun

Rate of growth:

Fast-growing

Soil:

Moderately fertile, moist, well-drained soil

Hardiness:

Borderline hardy (will need protection in winter in colder areas)

  • InformationThis bulb dies back after flowering each year and enters a period of rest ahead of regrowth the following season.
  • InformationHumans/Pets: Ornamental bulbs - not to be eaten

Product options

Add to basket
Product options image
BU30003098
1 × tuber
£5.49
shipped within 2 weeks
Remove Add
Product options image
BU30003214
3 × tubers
was £16.47 now £14.00
shipped within 2 weeks
Remove Add
Delivery options (pick your preferred option at checkout)
Standard delivery Bulbs (only)£4.95

Goes well with

Become an RHS Member today and save 25% on your first year