COOL GREY

The steel-grey, teasel-like flowers of the giant sea holly Eryngium giganteum ‘Silver Ghost’ add a stylish sculptural note from June through to the end of August.

H&S: 0.6x0.4m, £18/three

9cm pots, waitrosegarden.com

MIDNIGHT BLUE

The deep blue pom-poms of towering Agapanthus

‘Midnight Star’ add drama to the garden and are the star of any colour show from July until late summer.

H&S: 0.4m, £8.99/9cm pot, crocus.co.uk