How to Build a Rain Garden

Using a shovel or an excavator—you can rent one for about $230 a day or just hire an operator—dig down to the depth you need. Create a flat bottom so that water will percolate down evenly. If the rain garden is on a slope, you can pile some of the excavated soil into a berm on the low side to retain the water. For stability, stomp the berm soil down well and make the base at least 2 feet wide and the top at least 1 foot wide. The peak of the berm should be at least 6 inches higher than the water level when the rain garden is full. Also excavate for a dry well, if included; the one for this rain garden is about 2 feet square and 3 feet deep.