Rock Garden Plant Ideas for Sunny Sloped Locations

Snow-in-Summer

• Grow the herbaceous perennial called snow-in-summer (Cerastium tomentosum) as a ground cover in sun-splashed parts of a sloping rock garden. This native to western Asia and Europe tolerates a wide range of soils as long as they do not hold water. Snow-in-summer produces a vegetative mat about 6 inches tall, with its flower stems rising above to turn out clusters of white flowers. Snow-in-summer will "carpet" an area with its white flowers, notes the Missouri Botanical Garden. The plant is not appropriate for rock gardens in the deep south, as it does not withstand hot summers well. Use it in U.S. Department of Agriculture plant hardiness zones 3 through 7.

Mother-of-Thyme

• Mother-of-thyme (Thymus serpyllum) will develop over sloping ledges and grow over small rocks in a sunny location. This species survives as far north as USDA zone 4, according to the University of Connecticut Plant Database. Non-native to North America, mother-of-thyme grows in the form of a spreading mat only about 3 inches high. The woody perennial will bloom in June and July in a full sun habitat, with the pink flowers attracting butterflies. Mother-of-thyme will remain evergreen during the warmer winters. The plant suffers when placed in a damp area, as root rot will adversely affect its progress. Mother-of-thyme's foliage is aromatic.

Spring Heath

• A plant that grows in the mountainous terrain of southeastern and central parts of Europe, spring heath (Erica carnea) will flourish on sunny slopes. Useful in rock gardens as a plant that brings color in the early spring, spring heath blooms as early as the end of March. Growing to 12 inches, the evergreen shrub features bright green needles. The flowers are red-to-pink, but various cultivars will produce white and crimson blossoms. Spring heath does require a damp site with acidic soil. Cold hardy to USDA zone 5, spring heath will experience injury from the low temperatures of an extreme winter.