A stone retaining wall around a tree can create a uniform look to a yard, enhance curb appeal and add depth and interest to a landscape. A retaining wall around a tree can be created with almost any type of field stone or preformed pavers. Pavers or flat stones are much easier to work with since they are more uniform in size. Although it is also possible to construct a wood retaining wall, a stone wall is described here because wood is more susceptible to rotting than stone.
Attach a piece of string the length that you want the wall away from the tree base to a large nail. Pull the nail taut and use it make sure the wall is built at the right distance from the base of the tree.
Dig a level circle around your tree between three and six feet in diameter. If the ground is already mostly level, then the ring should be about four to six inches deep. If you are digging into a slope, then you will need to dig to a depth that makes the circle level all the way around. Make sure the ring is wide enough to accommodate your stones or pavers.
Place crushed or pea gravel at the base of the ring to a depth of about one inch. Use a construction compactor or piece of 4-inch-by-4-inch lumber to tamp down the gravel.
Place your stones on top of the gravel in the ring so that they are aligned properly. Use a carpenter's level to make sure they are straight and can be built upon.
Mix your masonry cement in a bucket with water according to the manufacturer's instructions.
Use a putty knife or offset spatula to apply a thin layer of the cement on top of the first layer of rocks.
Place the next layer of stones on top of the first layer. The joints of the second layer should meet in the middle of the first layer so that the joints are not lined up.
Continue layering in this manner until the wall is the height you desire. If you are building into a slope, it should be high enough so that there is about a foot of space between the slope and the top layer of stone.
Allow the wall to dry and cure according to the cement manufacturer's instructions and then backfill the ring with topsoil or compost. Plant annuals or perennials in the ring to add interest to your yard and take advantage of the additional planting space.