A rock garden is a popular type of garden for xeriscaping, or capturing the feel of desert and alpine terrains. A rock garden may be planted with any type of plants that grows well in rocky terrain, from mountain wildflowers to desert cactus to the rocky terrain used to simulate water in Japanese gardens. The design of these gardens, including borders, should fit with the theme of the garden.
In Japanese gardens, dry rock is used to symbolize water. A dry riverbed may be representative of a rushing stream beneath a bridge or bordering an island of color. Good borders for these dry riverbeds include large rocks that become reminiscent of mountains. The dry rock streams meander around the mountain border in the way that a real stream moves fluidly around obstacles. Other good borders for a dry steam bed of rocks include unevenly shaped plantings of odd numbers of plants.
Many homes have ditches planted in front of them to catch runoff and channel it away from the home and into a city's sewer system. But some gardeners use this lawn space to create a rock garden that borders the lawn. A swale garden may be filled with rocks and plants that drink from runoff during wet periods. During dry periods the swale garden filled with rocks resembles a dry stream bed. These gardens may be bordered by marshy plants that would be considered marginals in a water garden, such as bulrushes, cattail or Louisiana iris.
Alpine gardens are a popular garden type for those with hilly land. The rocks can be partially dug into a hillside to create terraces, and plants can be partially stuck under the rocks to seem as if they are spilling out of rock walls or over the edges of the stone. These plants create interesting borders because they seem as if they are bursting from the seams of the rock garden. Some popular plants to plant in the borders of rock gardens include moss pink, basket of gold, candytuft, soapwort, and hens and chicks.
Desert gardens are popular in xeriscaping because they use plants that are adapted to the climate to cut down on the frequency that water is required. Plants are placed together in a yard based on similar watering requirements. Often they are placed at the bottom of a runoff or in a low spot in the yard to take advantage of rain when it occurs. Visual and textural interest may be created by adding stones or bark in multicolors to serve as mulch. Good borders in desert gardens include herbs such as English lavender or creeping thyme.