How to Build Rock Planters

Spread a garden hose or powdered chalk over the ground to outline the shape of the planter. Keep it under 3 feet wide, since you will access it from one side only. Add to the desired planter width an additional 12 inches to provide space for stacking the rocks.

Dig a 5-inch-deep and 12-inch-wide trench just inside the hose or chalk mark. Use a shovel to dig the trench, and collect the dirt in a wheelbarrow or create mounds nearby.

Tamp the base of the excavation to provide a stable foundation for the mortarless rock-planter assembly. Fill depressions in the dirt with topsoil and tamp again so the trench is completely level.

Stack the rocks in piles nearby to reduce time during assembly. Place the largest, heaviest rocks in one pile, medium-sized rocks in another and the smallest in the third. Also form a pile comprised of small, irregular-shaped rocks to use for filling gaps between the planter walls.

Set the largest rocks in the 12-inch-wide strip to form the foundation of the planter. Place the largest rocks over the corners and other large rocks in between. Make sure the rocks in the row touch each other without overlapping.

Step back and examine the foundation row after laying the rocks over the excavated strip. Tamp the rocks in place to keep them from shifting. Measure the height of this row so you know how many more rows you can add without making the planter higher than 18 inches.

Lay medium-sized rocks over the base row to form the second row. Lower each rock on its flattest side so it rests firmly over the row of rocks under it. Ensure the rocks in this row touch each other but do not overlap. Once complete, measure the height of the planter to determine how many rows to add until complete.

Stack the smallest, flattest rocks on the top of the planter to form the last row. Examine the planter wall for any gaps, and fill with tiny rocks or small stones to close them. Pack dirt into the gap between the planter and trench, and hose it lightly so it sets in place and holds the rocks in the foundation firmly.

Spread a sheet of landscape fabric over the base of the planter, and add a few large rocks to assist in drainage. Fill the planter with topsoil to 4 inches from the top.