The rock garden was a nineteenth century inovation. It derived from the Mixed Syle of garden design, which had theme gardens based on ideas from various parts of the world and also from historical periods. The rock garden was intended to evoke the mountain scenery of the Himalayas and the Alps and the plants were drawn from these regions. This often required wet conditions for the roots (as in mountain clefts) and cold dry conditions for the leaves and flowers. These conditions can be created by making rockeries in glass houses.
See also: history of planting design.
A rock garden planting design in an Alpine House