Rock gardens are ideal for sloping areas for a number of reasons. If the slope is south facing, it gives the plants that are interspersed with the rocks more direct sunlight. The combination of rocks and plants can offset problems with erosion. In addition, covering a slope with a rock garden removes the necessity of mowing it, which can be difficult on steep slopes. If you have a slope with erosion problems, position rows of rocks so that they direct water sideways across the slope. This will help to prevent gullies from forming and washing away your topsoil.
Herbs and rocks go well together. Because herbs tend to be small, with shallow and spreading root systems, they grow well in the spaces between stones. Properly placed, the stones can act as a form of mulch, preventing larger and stronger plants from invading and choking out your herbs. The stones also act as thermal mass for regulating the temperature of the soil. Stones store up heat during the day and release it slowly overnight, thus keeping the soil warmer through cold nights and allowing herbs to produce farther into the fall.
A Japanese rock garden is the highest expression of the aesthetic and symbolic possibilities of stone, rock, gravel and sand. In traditional Japanese rock garden design, stones are used to symbolize mountains and specific landscapes, while raked gravel and sand are used to symbolize water. Japanese rock gardens can be created with or without water features, and can be tiny, taking up only a corner of your yard, or enormous and awe inspiring, as is the Ryoanji garden in Kyoto.
Rocks and stones can be used to good effect in conjunction with water features, such as ponds or streams. If you are lucky enough to have a natural water feature on your property, you can arrange rocks and plants to harmonize with and accent your water. If you don't have natural water, small ponds can be created using excavated holes and pond liners. Rocks and stones can then be used in the surrounding landscape, or even emerging from the pond itself for a more dramatic effect.