Erodium x variabile ‘Bishop’s Form’ – This Storksbill much resembles a miniature hardy geranium, to which it is closely related. It forms a flat pancake-shaped mat of dense scalloped green leaves with bright pink flowers (with dark purple veins) from May through to Sept. This perennial is easily overwhelmed by larger plants. Grows 2-4″ high by 12″ wide. Zone 6.
Lithodora diffusa ‘White Star’ – This sport of ‘Grace Ward’ was discovered in California in 2004 and introduced by Blooms of Bressingham in 2008. It features bright blue flowers (from May to June) with perfect inset white stars over narrow deep green leaves. ‘White Star’ prefers neutral to acidic soils and little fertilizer. Grows 6-9″ high by 18″ wide. Hardy to zone 6.
Phlox subulata ‘Millstream Daphne’ – This Creeping Phlox features bright pink flowers (with a darker rose-pink eye) from April to May over a mound of dense foliage. It makes a good flowering groundcover but needs to be sheared back after flowering. This is an excellent choice for slopes and rocky hillsides. Grows 4-6″ high by 12-18″ wide. Hardy to zone 3.
Gentiana acaulis – The Trumpet Gentian can be a bit tricky to grow but few plants provide such a beautiful display of true blue flowers. The blooms are borne from April to May (with the odd flower in summer) just over the dense rosettes of pointed, glossy green leaves. This native of the Alps prefers fertile, well drained soils. Grows 4 to 6″ high by 12 to 14″ wide. Hardy to zone 3.
Arabis x arendsii ‘Compinkie’ – This Pink Wall Cress bears fragrant bright pink blooms from mid to late spring and should be sheared back lightly after flowering in order to maintain a dense canopy. The flowers are borne over greyish-green foliage (evergreen) that is drought tolerant once established. May be grown from seed. Grows 6-8″ high by 1 to 2′ wide. Zone 3.