This evergreen perennial bears strap-like leaves and naturally grows in a clump form. The purple flowers produced throughout summer and can grow up to 30cm in diameter when mature. If you're looking for a plant that is going to really stand out from the crowd, this is the one.

At a glance:

Evergreen foliage

Lavender blue flowers throughout summer 

Full sun

Well drained fertile soil

Half hardy

Will reach a height of 1m and a spread of 1m over 2-5 years