A rock garden is defined as a garden where gravel and rocks are combined with drought loving plants to give a dramatic and natural look. Miniature rock gardens have a history that can be traced to China and Japan where they used rocks for decoration and symbolism in their garden. A miniature rock garden uses small Alpine and trough-style plants that grow well in a rocky environment to create a compact garden.
The rock thyme plant, Acinos aplinus, is a small, evergreen groundcover that produces trailing foliage. The plant grows to a height of 2 inches and width of 8 inches and produces violet-red-colored flowers in June through October. Rock thyme is hardy to plant in USDA growing zones 4 through 9 and prefers full sun conditions and dry soil found in rock garden landscapes. The plant is native to southern and central Europe, where it is found growing along the rock hillsides.
The mat daisy, Raoulia subsericea, is a groundcover growing plant that produces gray-green foliage with white flowers that bloom in the summer months of July and August. The plant is hardy to plant in areas that do not drop below 0 degrees F in the winter months. Plant a mat daisy in a rock garden location that has a course, nutrient rich soil and full sunlight conditions. Mat daisy requires winter protection in areas that are wet, to prevent standing water around the plant.
The bees ruby plant, Armeria pseudoarmeria, is an evergreen that produces tufts of leaves and bright pink flowers. The flowers form on the ends of wiry plant stems and reach a height up to 12 inches. Bees ruby is hardy to plant in USDA growing zones 6 and 7, where the winters are not harsh and the summers are mild. The plant will grow in the poor to moderate nutrient soil of a rock garden but does require full sunlight conditions.
The garden drop plant, Onosma rigida, is a small perennial native to southeastern Europe. Garden drop grows to a height of 10 inches with dark green narrow leaves and yellow tubular flowers that bloom during the summer months. The plant grows well under the dry conditions of a rock garden and is hardy in USDA growing zones 5 through 8 as long as the area is well draining, especially during wet winters.
The cyclamen-leaved violet, Viola coreana, is a shade loving groundcover that grows to a height of 4 inches and width of 6 inches. The plant will self sow itself if the blooms are allowed to go to seed and break open. Cyclamen-leaved violet produces silver and green marbled leaves with small blue-violet colored flowers that bloom during the months of April through June. Plant this violet species in an area of the rock garden that has partial to full shade light conditions and a well draining soil. Cyclamen-leaved violet is native to areas of Asia and winter hardy to a temperature of -10 degrees F.