Japanese dry riverbed gardens are one form of the Karesansui-style gardens. The name means "dry landscape." Carefully arranged rocks, representing islands, sit in the middle of a pond or dry riverbed, both made of pebbles. In the pond, the pebbles are raked to form ripples that look like waves. In the dry riverbeds, the rocks are methodically placed giving the impression of a natural riverbed with the pebbles representing the water. Some of these dry meditation gardens use plants as accents.
Moss is sometimes used for a bit of colour in a dry riverbed garden. Sometimes, the moss grows naturally, other times it is meticulously planted on certain parts of the rocks. The intent is to make the islands, or in the case of rocks around an imaginary shoreline, the mountains, look authentic. The use of moss goes back to the Edo period, 1603 to 1867, in Japan, when this plant was used in Karesansui gardens as a colour contrast for the natural earth tones of the raked gravel or pebbles. Moss pulls moisture from the air, making it ideas for dry riverbed settings.
Bonsai trees are miniature versions of large tree varieties. They are used in Japanese gardens of all varieties but in the Karesansui, or dry garden, they add a subtle bit of colour. Since they are potted, they also can be moved or brought inside if the weather turns too hot or cold. Considered an art form, these tiny trees are created by cutting, shaping and tying off branches in a precise manner in order to inhibit growth. One Japanese white pine on display at the United States National Arboretum is almost 400 years old. Other types of trees that work in a dry Japanese garden include maple, oak and juniper.
Bamboo is commonly used in dry riverbed and other types of Karesansui dry gardens. It grows rapidly, provides colour and quickly creates a natural privacy barrier. Use bamboo at various points along your riverbed to simulate forests, or to surround your garden entirely to create your own personal meditation space. Karensansui gardens are intended as meditation gardens. Clumping bamboos, such as the Timor black or the Himalayan weeping bamboo also do well in smaller dry garden layouts and in atrium settings.