Centaurea macrocephala (Giant knapweed): Huge, bright yellow almost fluffy flowers in mid-summer follow attractive papery buds. Attractive to bees. Height to 1.5m. Hardy.

Cephalaria gigantea (Giant scabious): Very tall wavy stems topped with large lemon yellow scabious-like flowers.Easy to grow. May need staking or support. Hardy. Up to 2m. [Collect Only]

Rudbeckia subtomentosa 'Little Henry' (PBR): Yellow quilled flowers with chocolate brown centres in late summer. Compact variety with a delightful vanilla scent. Hardy. Up to 90cm. [Collect Only]

Sisyrinchium striatum: Open fans of strappy iris-like leaves topped with lemon yellow flowers in summer.