• Velvety purple to marron blooms of a Dahlia
1 1

Dahlia Black Jack

  • Dramatic dark blooms add garden depth
  • Easy tuber planting with simple care
  • Blooms throughout summer with regular attention
  • Perfect for cutting and garden display
PRE ORDER Estimated Shipping date: Early to Mid February 2026
Tubers
£15.55
£15.55
Tax included. Shipping calculated at checkout.
Dahlia 'Black Jack' creates a striking display with its dramatic, dark blooms that add depth to any garden setting. Supplied as dormant tubers (not growing plants). Plant tubers 10–15cm deep and 30–40cm apart in well-drained soil after the last frost for best results.
Pot sizes explained

At Newlands Nursery we grow and sell plants in a variety of different sizes, from small starter plants up to planted containers. 

We know it can be tricky to picture the size of each plant. This page gives you an idea of the size of the plants we are sending out.

Please keep in mind that plants vary from one season to the next. The size of the plant refers to the pot or plug it is grown in, rather than the height of the plant, unless specifically mentioned on the plant page. 

Picture of plug plant size

Starter Plant (Plug Plant)

Plug Size: 2cm by 4cm. Our most popular size. This is often the most economical way of buying plants and is a great way to get a head start on the season. Generally this size is best to be potted up before planting out.
Picture of Jumbo plug plant

Jumbo Plug

Plug Size: 6cm by 7cm. A fantastic alternative to a 9cm pot and saves on plastic too. The plants in this size are well established and give you a head start. This size is perfect for planting straight into containers and baskets as well as the garden.
Picture of 9cm pot

9cm pot

Pot size: 9cm by 9-10cm. This size hold some well established plants, some of which maybe around 1 year old. We sell most of our ranges in this size and most of the plants sold in this size, are established enough to be planted straight outside.
Picture of 13cm or 1 litre pot

13cm or 1 litre pot

Pot size: 12-13cm by 12-15cm Currently our largest size of plant, with the exception of our planted containers. Many of our House Plants are available in this size, as well as some special collections and varieties.

    Velvety purple to marron blooms of a Dahlia
    Planting Calendar
    Jan
    Feb
    Mar
    Apr
    May
    Jun
    Jul
    Aug
    Sep
    Oct
    Nov
    Dec
    Jan
    No
    Feb
    No
    Mar
    No
    Apr
    Yes
    May
    Yes
    Jun
    Yes
    Jul
    No
    Aug
    No
    Sep
    No
    Oct
    No
    Nov
    No
    Dec
    No
    Flowering Calendar
    Jan
    Feb
    Mar
    Apr
    May
    Jun
    Jul
    Aug
    Sep
    Oct
    Nov
    Dec
    Jan
    No
    Feb
    No
    Mar
    No
    Apr
    No
    May
    No
    Jun
    Yes
    Jul
    Yes
    Aug
    Yes
    Sep
    Yes
    Oct
    No
    Nov
    No
    Dec
    No

    Dahlia Black Jack - Plant information

    Size: Grows to approximately 90cm tall with a spread of 40cm.

    Position: Thrives in full sun with well-drained soil. Avoid heavy shade to encourage strong growth.

    Feeding etc: Feed monthly with a balanced fertiliser during growing season. Remove faded flowers to encourage more blooms.

    Care: Plant tubers 10–15cm deep and 30–40cm apart. Protect from frost during winter. Keep soil moist but not waterlogged.