A rock garden is a garden composed of large and small rocks, placed in the soil, and highlighted by plants which fill the spaces in between the rocks. It provides a quiet, calm juxtaposition to lush, full flower beds and masses of green. Whether settled on a hillside, around a curve in the yard or tucked away beside a structure, a rock garden in the shade provides a peaceful spot to work, rest or think. Plants for rock gardens are usually on the smaller end; think dainty flowers and creeping ground covers that will settle in and around the rocks and highlight rather than overpower them.
Fernleaf Bleeding Heart
Fernleaf bleeding heart (Dicentra eximia) is a diminutive plant that enjoys light shade. Its height won't get above 18 inches. This perennial produces heart-shaped, pink or red flowers which hang gracefully on curving stems. Its daintiness suits a rock garden well. Though it is often found in moisture woodland soil, it will grow adequately in a rock garden's drier ground.
Most ferns (onoclea and polypodium), though known to be shade-loving plants, are most often also moisture-loving plants, and the drier ground of a rock garden doesn't always suit them. A few varieties, however, do well in a rock garden and won't complain about drier soil. Look for Common Polypody (Polypodium virginianum), which is a smaller fern, with deep green fronds from 6 to 12 inches long. Sensitive fern (Onoclea sensibilis) is a larger option; its green fronds can grow 12 to 18 inches long and have larger leaflets on yellow or tan stems.
Bugleweed (ajuga) is a quick-growing, perennial ground cover that will fill in those spaces between rocks quickly. If several bugleweed plants are put in the soil about 12 inches apart, they will grow to fill the intervening space within one season. It likes shade and doesn't like to be planted deeply, which is nice when working in drier, rocky soil. The foliage of bugleweed can be green to purple. It produces spiked flowers in the spring; some varieties have red blooms and some have white. Though bugleweed likes moist soil, it grows very well even in drought conditions.
Heartleaf bergenia (Bergenia cordifolia), a perennial, will be happy with partial shade, especially afternoon shade. Bergenia offers two features: thick leaves that are almost rosette-like in shape and pink flowers on stems that grow about a foot high.
Coral bells (Heuchera sanguinea) grows in a mound-like habit, with variegated leaves in dark-green, sometimes with purplish accents. This perennial loves the shade and will bloom all summer: the flowers are small and dainty, held aloft on 18 inch stems. They can be white, pink or red.