To install scalloped lawn edging, use a trowel to cut a trench that is approximately 5 inches wide, and level the bottom of the trench to create a smooth, even surface. Place the scalloped edging in the trench, and use a rubber mallet to tap the edging into place against the adjoining surface. Continue placing the pieces of edging side-by-side, tapping the top and side of each piece with the mallet to tighten it, and back-fill the trench with soil.
When working with clay or other dense soil, dig the trench approximately 4 inches deeper, and line the bottom of the trench with a 3-inch layer of compacted gravel topped with a 1-inch layer of coarse sand. The trench should be deep enough to cover the bottom half of the edging.
To cut the final piece of edging to fit, measure the piece to fit the available space. Score the piece of edging by tapping a brick chisel with a mallet. After scoring around the piece of edging, hit one side of the edging with a mallet to break it at the score mark.
If the edging is located beside a flower bed, back-fill the same side of the trench with mulch, and back-fill the opposite side of the trench with soil.