How to Use Rocks to Build a Raised Garden

Raised beds allow the gardener to solve several issues in the garden. If the soil doesn't drain well, or is rocky and hard to dig, a raised bed brings the garden above the problematic soil. By using rocks that are already in the yard to build raised beds, you can resolve another problem -- what to do with the rocks when you remove them from the lawn and other garden beds.

The naturally weather-beaten rocks from the yard or local area tie the garden bed to the landscape. Whether building a wildlife garden or planting vegetables, the stones are a free resource for the gardener. Avoid rounded stones when building a dry-stacked wall; stones with flat, rough edges fit together and stack nicely into a sturdy wall.

Stone can be purchased as blocks, making it simple to stack the stones in a running-bond pattern. The stones fit tightly together, allowing you to fit them together in a rectangular, square or rounded garden bed. You can mortar the stones for a permanent installation, or dry-stack them for a semipermanent bed.

Raised beds should be at least 1 foot deep and no more than 3 to 4 feet wide, so you can reach the plants in the center of the bed. The rocks, depending on their size, may be placed in one row around the bed or stacked high enough to also provide a seat for you while weeding. Raised beds built for mobility-impaired gardeners are generally 24 inches tall, allowing the gardener to reach into the garden from the wheelchair.

Tape measure

Landscapers paint

Shovel

Hand tamper or plate compacter

Landscape fabric

Crushed gravel

Spirit level

Large rocks or stones

Hammer

Chisel

Measure and mark the perimeter of the raised bed using a tape measure and landscapers paint. The bed may be any shape, but avoid making it wider than 4 feet at its widest point.

Wear protective gear when using spray paint, digging, working with the rocks and building the raised bed. Heavy work gloves, boots, long pants, a long-sleeved shirt and safety glasses protect your skin and eyes from flying debris while you work. Add a wide-brimmed hat and sunscreen to prevent sunburn. 

Avoid using river rocks unless you are only building it one or two rows high. Round stones tend to roll, making the bed's wall unstable.

Remove all vegetation and soil to a depth of 4 inches around the perimeter of the garden bed. The trench should be 24 inches wide to provide a stable base for the rocks.

If you are also building a garden path around the raised bed, add 36 inches to the width of the trench. This is wide enough for a wheelchair gardener to access the garden.

Tamp the soil in the trench firmly with a hand tamper or plate compacter. Cover the soil with landscape fabric, which helps prevent the gravel from sinking into the underlying soil.

Add 3 inches of crushed gravel to the trench. Dampen it with a garden hose and hand sprayer. Tamp the gravel firmly. Use a long board and a spirit level to see if the gravel's surface is even. Add more gravel if necessary to low spots and tamp again.

Lay the first row of rocks in the trench. Use the largest rocks for the bottom row. Fit the stones together tightly, with slanted or lower edges facing into the garden bed. If necessary, chip off edges with a hammer and chisel to make the rough stones fit together.

Add a mixture of equal parts garden soil, compost and peat moss to the garden bed as you finish building each row of stones. Tamp the soil against the wall to fill in the small gaps between the rocks.

Add a second row of rocks, with each rock overlapping the joint below it. Fit the rocks together, using smaller rocks as shims where the larger rocks don't quite fit together. Set the second row slightly back from the first, so the wall leans back into the garden bed at a rate of 1 inch per 1 foot of the wall's height.

Add rows of rocks until the wall is the desired height. Check with the spirit level to ensure that the walls are even. When building the last row, use the flattest rocks with the smoothest side up as a cap to the wall.

Finish a surrounding path by filling the rest of the trench with crushed gravel. Dampen the gravel again and tamp it firmly, until it is a solid surface.