How to Edge a Lawn

The best method for edging a lawn depends on the type of grass and the amount of free time you have. Some grasses grow in clumps and spread slowly, but others quickly invade flower beds, spreading through shoots called rhizomes that grow below ground. Lawn edging solutions range from regularly trimming the edge with a spade or edging tool to building a physical barrier of bricks or other hardscaping materials.

Regular cutting is all that's needed to maintain a lawn edge when growing cool-season grasses, but in a lawn of warm-season grasses, a physical barrier is the best low-maintenance solution. Perennial ryegrass (Lolium perenne), which grows in U.S. Department of Agriculture plant hardiness zones 3 through 9, and tall fescue (Festuca arundinacea), which grows in USDA zones 4 through 7, are cool-season lawn grasses. Both grasses are slow to overgrow a lawn edge, and they require trimming once a year or less. The warm season grasses Bermuda grass (Cynodon dactylon, USDA zones 7 through 10) and zoysia grass (Zoysia japonica, USDA zones 5a through 10) spread vigorously. Only a physical barrier set 6 inches deep contains their rhizomes.

A cut lawn edge is a V-shaped trench between the lawn and garden beds or borders. Cut the edge with a broad-bladed spade or half-moon spade made for edging lawns. Standing on the lawn, push the spade 4 to 6 inches deep into the lawn edge and lever it upward. Cut the rest of the edge in the same way, and remove the cut pieces of lawn. Rake a slope in the soil from the trench bottom into the bed or border. When grass begins to overgrow the trench, cut it again with a spade, or use a power edger, weed trimmer, hoe or edging knife. Wear leather gloves, long pants, a long-sleeved shirt and safety goggles when using power tools.

Pavers or bricks form a neat flat edge between a lawn and garden beds. When mowing a lawn with a flat edge, the mower wheels run over the edge, and the mower blades cut the spreading grass. Dig a trench 2 inches deeper than the pavers or bricks and the same width, at the lawn edge. Spread a layer of landscape sand 2 inches deep over the trench base, and smooth it flat and even with a piece of wood. Lay the bricks or pavers on top, and check that they're level and even with a builder's level. Push sand into the gaps to help fix the pavers or bricks in place.

A physical barrier 6 inches deep and protruding 4 inches above ground provides a lawn edge that controls invasive grasses. Commercial plastic and metal edging strips, log rolls, lumber and cedar shakes are some options. Redwood, cypress and cedar are rot-resistant and long-lasting. Dig a trench as deep as needed so that 4 inches of the edging will protrude from the soil. For example, if the edging material is 10 inches deep, dig a trench 6 inches deep. Place the edging in the trench and use a builder's level to check that it's level. Push soil in to fill any gaps. After mowing, use hand shears or a power trimmer to trim the grass next to the edge that the mower doesn't cut.