Geranium maculatum 'Album' (white spotted cranesbill): Clean white flowers over neat foliage. Great for establishing under trees and in shady areas.

Tradescantia (Andersoniana Group) 'Innocence' (Spider lily 'Innocence'): Three-petalled pure white flowers with purple tinged anthers. Strappy bright green foliage.

Vinca minor f. alba 'Gertrude Jekyll' (Small white periwinkle 'Gertrude Jekyll'): A compact mat-forming evergreen perennial with trailing stems of dark green leaves. White flowers from mid spring to autumn.