A rock garden is barren and drab without the addition of a dash of green or a splash of colour. Perennial rockery plants persist year after year, thriving in shallow soil with little moisture. Some are even evergreen, and most produce flowers during various parts of the year.
Ground cover plants
Creeping thyme, aubretia and iberis are profusely blooming ground cover plants with foliage that is evergreen. These plants will spread over a large area and attractively cascade over rock walls. Iberis has white flowers, creeping thyme blooms in pink to white, and aubretia cultivars exist in shades of pink, purple or blue.
Aster and dianthus are very hardy and provide abundant colour to the rock garden. Asters are tolerant to drought and cold and have a wide variation in flower colour depending on the variety. Most bloom in late summer to autumn. Dianthus can be evergreen in mild winters and has the added advantage of fragrant flowers in pink or purple. These ornamental perennials are low maintenance and drought-tolerant once established.
Crocus, grape hyacinth and dwarf daffodils perform reliably giving early spring colour to the rock garden. Autumn blooming crocus bulbs are available as well, including the saffron crocus. These bulb species are tolerant of neglect and drought; however, the soil should be well drained.