Euphorbia myrsinites – Donkey Tail Spurge has the look of an exotic succulent with its flowing branches of bluish-green leaves that trail up to 18″ long. This species is reliably evergreen and blooms in late spring with terminal flowers of pale yellow. As with most Euphorbia, the sap is a skin irritant – so use care when working with it. Zone 5 hardy.
Phlox subulata – Moss Phlox gets its name from its fine needled foliage but it’s the April to May flowers, which literally smother the plant below, that really impress. A few standard cultivars include ‘Emerald Pink’, ‘Candy Stripe’ (white & pink), ‘White Delight’, ‘Scarlet Flame’ and ‘Emerald Blue’ (pale lavender-blue). Ultimate height is 3 to 5″ tall. Zone 3 hardy.
Aurinia saxatilis (syn. Alyssum saxatile) – Basket-of-Gold is an old-fashioned rockery favourite with abundant late spring blooms of bright gold to pale yellow – depending on the cultivar. The evergreen foliage is hairy, giving it a silvery sheen and this species is reasonably drought tolerant, so it can work in areas without irrigation. Zone 3 hardy.
Dianthus gratianopolitanus ‘Firewitch’ (syn. Dianthus ‘Feuerhexe’) – A particularly floriferous form of Cheddar Pinks, with abundant magenta-pink single blooms with fringed edges and spicy clove-like fragrance. This 2006 Perennial of the Year selection should be sheared back to its evergreen bluish-grey foliage to promote reblooming. Fertilize sparingly. Zone 3 hardy.
Aubrieta x cultorum (syn. Aubrieta deltoidea hybrids) – Rock Cress is a classic choice for the sunny rock garden, with its trailing nature (up to 2′ long) and wide range of flower colour. Some of the better cultivars include ‘Whitewell Gem’ (violet-purple), ‘Royal Red’ (vivid red), ‘Royal Blue’ (violet-blue) and ‘Dr. Mules’ (purplish-blue). Shear back after flowering. Zone 4 hardy.