(All pot sizes are approximate)
Buy Arid, Succulent plants online

Fully hardy - requires no frost protection.
Aciphylla glaucescens - 1Ltr £9.99
(Bayonet plant, Feathery blue Spaniard), Family Apiaceae, Originating from New Zealand. An architectural mound-forming evergreen perennial with rosettes of rigid, narrow blue/green leaves up to a metre long, with fearsomely spiky tips.

Fully hardy - requires no frost protection.
Yucca filamentosa 'Color Guard' - 9cm pot £5.99
(Adam's Needle), Family asparagacea, Originating from USA. A stemless Yucca forming rosettes of lance-shaped, blue-green leaves with a thick yellow central band.

Fully hardy - requires no frost protection.
Yucca gloriosa 'Variegata' - 1.5Ltr £9.99
(variegated Spanish dagger), AGM, Family Agavaceae, Originating from Southeast USA. A multi-branching, small, tree-like Yucca, with a rosette of green, boldly striped yellow, straight, stiff leaves with very finely serrated margins.