Phormium ‘Black Adder’

(New Zealand Flax 'Black Adder')

By August 27, 2025
Rows of planted Phormium 'Back Adder' shrubs with sword-like purple-black leaves growing upright and slightly arching at the ends. Commonly known as New Zealand Flax

About Phormium ‘Black Adder’ (New Zealand Flax ‘Black Adder’)

Phormium ‘Black Adder’ PP20451 is prized for its its uniform, modern look. Its purple-black sword-like leaves grow upright reaching an average mature landscape size of 3-4′ tall by 3-4′ spread but can grow larger under the right conditions. Keeping its beautiful, glossy leaves year-round, reddish flower stalks can emerge during the summer months depending on climate conditions.

Origins And Landscape Adaptability 

This variety originates New Zealand and is a hybrid of Phormium tenax and Phormium cookianum. It’s exceptionally adaptable to Northern California climates and a great deterrent for rabbits and deer. Drought tolerant once established and winter hardy to temperatures as low as 15 degrees Fahrenheit while also durable against salt spray and windy coastlines.

Care And Planting Instructions

Plant New Zealand Flax ‘Black Adder’ in an area that receives full to partial sun exposure using well draining soil. Water regularly after planting to help it establish quickly to its new location, then reduce frequency. While drought tolerant once established, this Flax variety looks best with regular irrigation during hotter months. Remove dead leaves for a cleaned up appearance and divide in the spring if desired.

Landscape Design Ideas 

A delightfully interesting shrub that fits modern landscape designs to rock style gardens. Its large but not overbearing size would make it ideal along a pathway or planted in containers to frame an entrance. This variety comes in an array of colors such as green, red and yellow. Read more about our other phormiums.


Botanical Name: Phormium 'Black Adder'

Common Name: New Zealand Flax 'Black Adder'

Average Landscape Size: 3-4' x 3-4'

Plant Type: Evergreen

Bloom Color: Reddish

Foliage Color: Purple-Black

Forms: Shrub

Sizes: 5 Gallon

Special Features: Deer Deterrent, Dramatic Color, Drought Tolerant, Easy Pruning, Good For Container Or Ground Planting, Good For Erosion Control, Good For Mass Plantings, Low Maintenance, Ornamental Plant, Tolerates Light Frost, Waterwise, Year-round Interest,