Dianthus: Rockery Pink has several dwarf varieties that are suitable for the rock garden. The Rockery Pinks form either neat cushions or spreading carpets of grey or green grassy foliage. These leaves are covered by the sweet smelling and generally fringed flowers in May or June, just as the display of the popular spring flowering alpines comes to an end. Pink is the usual colour but whites, reds, purples and even one yellow (D. knappii) are available. As a general rule the Rockery Pinks like but do not insist on chalky soils but they all hate clayey ones. Varieties: Choose D. alpinus (Alpine Pink) if you want large one inch flowers on neat cushions of green foliage, height four inches, spread six inches, flowering period from May to August. The dark eyed blooms are available in pink, white or purple. D. deltoides (Maiden Pink) is an old favourite, height eight inches, spread ten inches, flowering period June to September. Pink is the usual colour but there is also white ('Albus') and bright red ('Flashing Light'). For covering large areas pick the carpeter D. caesius (D. gratianopolitanus), height eight inches, spread two feet, flowering period is May to July. Miniatures include D. erinaceus and D. freynii (height two inches, flowers small and pink). D. neglectus (D. pavonius) is unusual, the flowers do not appear until July and August and the pink petals have a biscuit coloured reverse. In addition to the species there are many miniature hybrids, such as 'Little Jock' (pink), 'La Bourbrille' (pink) and 'Nellie Clark' (red). Site and Soil: Requires well-drained open soil, thrives in full sun. Propagation: Sow seeds in spring or plant cuttings in summer.

Diascia: Twinspur is a popular sprawling rockery plant from S. Africa. Just two are offered for planting in the rock garden, both are dwarf and quite hardy but may die out if the winter is exceptionally cold. The flowering period is long and the flat-faced pink blooms are borne in great profusion. Look for the two spurs at the back of the flower, which give this plant its common name. Varieties: D. cordata forms a mat of wiry stems which reach about eight inches high. Loose heads of Nemesia-like flowers appear in June and continue to appear until September. Throughout this long flowering period the plant is covered with these rosy-pink flowers. The hybrid of D. cordata and D. barbarae was launched as D. 'Ruby Field' in the seventies and has become popular. It is taller than D. cordata (nine to ten inches) and the flowers are larger. Site and Soil: Requires well-drained soil and a sunny site. Propagation: Plant stem cuttings in spring.

Dicentra: Bleeding Heart belongs to the bed or border but there are smaller, feathery-leaved species for the rock garden. The popular dwarfs are easy to grow provided the soil is reasonably fertile and is kept moist in dry weather. In early summer the flowering sprays appear, arching stems bearing pendant locket-like flowers in white, pink or red. Varieties: D. cucullaria (Dutchman's Breeches) is a popular six-inch high rockery type, the flowers are white with yellow tips and appear in April and May above mounds of ferny foliage. As will all of the Dicentras, the leaves die down shortly after flowering. D. canadensis is quite similar, but the flowers are all white with just a touch of green. D. eximia (twelve inches) is a taller plant with pink-purple flowers from May to midsummer. D. formose (eighteen inches) produces pink blooms in early summer. D. peregrina is a difficult beauty; popular in textbooks but rare in the catalogues. Site and Soil: Any well-drained garden soil will do, thrives best in light shade. Propagation: Divide clumps after flowering.

Dodecatheon: Shooting Star is a plant for a moist and shady spot. It is often grown with Primulas as they both thrive under the same conditions. The common name comes from the shape of the flowers; the petals are swept backwards, revealing the anthers. These Cyclamen-like blooms are borne in clusters on top of an upright stalk. Varieties: The most popular species is D. meadia (American Cowslip), but it is not the best one for the rock garden. Basic details are height eighteen inches, spread eighteen inches, flowering period June to July. The usual colour is rose-purple, but a white variety (album) is available. A better choice is D. pulchellum also sold as D. pauciflorum and D. radicatum. The foliage is neater, the flower stalks shorter and the fine crimson variety ('Red Wings') grows only eight inches high. At the mouth of the flower there is a group of purple stamens. Site and Soil: Requires a moist but well-drained spot, thrives best in light shade. Propagation: Divide clumps in spring.

Dryas: Mountain Avens is an excellent prostrate plant for groundcover or clothing bare rocks. The creeping woody stems bear leathery evergreen leaves which are shiny green above and silvery below. Above this Oak-like foliage the large flowers appear on short stalks in late spring or early summer, and these blooms are followed by attractive silky seed heads in summer. Do not feed, flowering is disappointing in rich soil. Varieties: The popular species is D. octopetala, which grows wild in the mountainous regions of Britain and other European countries. The basic details are height four inches, spread two feet; flowering period is May to June. The blooms are about two inches in diameter and look like small Shrub Roses. There are eight white petals and a golden centre. Where space is limited grow the miniature variety 'Minor'. The American species D. drummondii bears yellow flowers. The hybrid of these two species is D. suendermannii with cream-coloured blooms. Site and Soil: Thrives in well-drained soil and full sun. Propagation: Plant stem cuttings in summer.

Edrainanthus: resembles the Campanula family. This low growing plant produces tight clumps of tufted foliage from which trailing stems arise. The flowers are open bells of blue, white or occasionally purple. They appear on short stalks in June and July. Not a difficult plant, but it is occasionally short lived. Its deep rooting habit makes it a good choice for dry situations. Varieties: E. pumilio is the pick of the bunch. It is compact, three inches high with a six-inch spread, and a mass of violet-blue flowers. These almost stemless blooms cover much of the silvery-grey foliage. The bells are one inch across. For flowers with are two inches wide choose E. serpyllifolius (Wahlenbergia serpyllifolia), height six inches, spread twelve inches. The large violet blooms form a ring around the edge of the tufted clumps. The variety 'Major' has the largest blooms. E. graminfolius has grassy leaves and almost stemless blue-purple flowers. Site and Soil: Requires well-drained soil, thrives in full sun. Propagation: Plant stem cuttings in summer.

Erica: Heather is sometimes rejected by the experts as a suitable plant for the rock garden. Yet these woody evergreens with their needle-like leaves and bell-like flowers have a number of distinct advantages. They are easy to obtain and grow, are not rampant spreaders and are available in a wide range of flower and foliage colours. By choosing varieties with care, you can have Ericas in flower nearly all year round. Varieties: Pick E. carnea (E. herbacea) for blooms between January and April, height nine inches, spread two feet. The blooms are borne on one side of the stem and there are many varieties ranging from pure white to deep red. A few well-known ones are 'Vivellii' (red foliage and flowers), 'Springwood White' and 'Springwood Pink'. This species does not demand acid soil, the others do. The Bell Heather E. cinerea (in bloom June to September) has many varieties, ranging from white to near black. E. tetralix (in bloom June-October) has grey foliage. Site and Soil: Requires well-drained soil and a sunny site. Propagation: Plant stem cuttings in summer.

Erigeron: Fleabane has several dwarf varieties for the rock garden, all bearing golden-centred flowers with whorls or ray florets in white, blue, pink, purple or yellow. They are easy to grow if the site is sunny and there is a long flowering season, but the smaller species tend to be short lived. Choose with care. Some species form neat clumps but one or two can be very invasive. Varieties: E. mucronatus (E. karvinskianus) is the most popular species but it is also the most invasive, spreading by runners and self-seeding. Keep it out of the rockery, use it instead in paving cracks and crevices between walling stones. Basic details are height six inches, spread two feet, flowering period June to October. Flowers darken from white to deep pink with age. Other species include E. aureus (height four inches, spread nine inches, golden flowers in June and July). The tiny E. compositus attains a height of three inches, spread five inches, with pale blue flowers from June to October. The much larger E. aurantiacus is twelve inches high, with a spread of eighteen inches and orange flowers from June to August. Site and Soil: Thrives best in well-drained gritty soil in full sun. Propagation: Divide clumps in the spring.

Erinus: Summer Starwort is a true alpine, growing wild in the mountains of Europe and sometimes seen as a naturalized plant in cracks and crannies in old buildings and walls. It is small and short lived, but this is not a problem as self-sown seedlings take over, providing small mounds of tiny green leaves. Clusters of small starry flowers appear on short wiry stalks. The splashes of pink, white or red last until midsummer sometimes longer. Varieties: There is just one species, E. alpinus. The basic details are height three inches, spread four inches; flowering period is from April to August. The toothed leaves are dark green and the flower colour is pink. At first glance the flowers look like five-petalled stars, but on closer examination they are seen to be two-lipped, with two lobes above and three lobes below. You can buy named varieties in different colours, such as 'Albus' (white), 'Dr. Hanele' (crimson) and 'Mrs. Charles Boyle' (pink). Site and Soil: Requires well-drained infertile soil and thrives in sun or light shade. Propagation: Sow seeds in spring where the plants are to flower.

Erodium: Storksbill has several species available for growing in a sunny rock garden. They are long-lived and not fussy about soil type. The foliage as well as the blooms is generally attractive. The usual flower colour is white or pink with a network of red veins, but there are exceptions. The common name relates to the long and beaked fruits. Varieties: The plants are nice but the names in the catalogues are often muddles. The most important species is listed as E. reichardii (E. chamaedrioides). It is a ground hugging plant which produces almost stemless flowers in June and July. Choose one of the varieties, 'Album' (white), 'Roseum' (pale pink) or 'Bishop's Form' (deep pink). All have reddish-purple veins on the petals. E. chrysanthemum (six inch high clumps) has yellow flowers in May and June. An odd point, male and female flowers occur on separate plants. E. corsicum is a silvery-leaved pink-flowered species which forms a mat rather than a clump. Others to look for are E. guttatum and E. petraeum. Site and Soil: Any well-drained garden soil, thrives in full sun. Progagation: Sow seeds or divide clumps in spring.

Euryops: is a member of the Daisy family from S. Africa and has become increasingly popular in recent years, but it is still missing from many catalogues and garden centres. It forms a rounded bush with attractive foliage and in late spring bright yellow flowers appear. When conditions are right the whole bush may be covered by the blooms, but in some seasons the number of flowers may be disappointing. Deadhead when flowers fade and cut the plant back hard every few years to maintain the compact growth habit. Variety: There is just one species for the outdoor garden, E. acraeus, sometimes sold as E. evansii. Basic details are height twelve inches, spread eighteen inches; flowering period is May to June. The ends of the branched stems are crowded with silvery-grey narrow leaves. This foliage is evergreen and the bush is hardy, making Europs a useful addition to any rock garden in winter. The flowers are about one inch across and are borne on eighteen-inch stalks. Site and Soil: Requires well-drained gritty soil in full sun. Propagation: Easy to propagate just plant cuttings in summer.