Dry stone walls can be built as freestanding structures or for supporting a bank. The former will require reasonably substantial foundations if they are more than a few courses high and their construction may need to be undertaken by a professional. Walls built up against banks for effect, rather than a support to unstable ground, are easier to construct. They should be built slightly away from the bank and all stones laid slightly sloped back for stability with free-draining compost added as a backfill. At intervals use a long stone at right angles going back into the bank for added stability.
Ideally, plant as the dry wall is being built, layer by layer. Roots can then be spread out and covered with 2.5cm (½in) of a suitable soil mix, such as equal parts good loam, peat substitute and sharp grit. Before adding the next layer of stones, place a few pebbles around the roots to keep the joint open. However, keep crevices within the wall small to prevent soil being washed out from behind. Alternatively, plants can be pushed into crevices after construction. When planting allow for plant growth and trailing habit.