Landscape edging plays an important role in pulling the landscape together. Edging function is simply, says Rhonda Ferree, Horticulture Educator with University of Illinois Extension. "It forms a clean, neat line between planting areas and turf or groundcovers." When installed properly, it should blend in with the landscape, minimize hand trimming, and help contain mulches within the bed areas.
"Beds can be edged by hand, but it is hard work and must be touched up once or twice a year." Rhonda says that she particularly likes the look of a hand-edged bed. "An edging area 4 inches deep and wide can easily contain bluegrass."
Start by using a sharp spade to cut an edge, and then remove the soil and grass to form a small cliff. You can leave it hand-edged like this or fill the space with something solid like steel, wood, brick, stone, or plastic.
The material used for edging should be long lasting, strong, and compliment the rest of your landscape. Ferree provides pointers about each type.
Metal edging, including steel and aluminum, is the longest lasting. Steel edgings have been around for more than 30 years but are relatively expensive, difficult to install properly, and has problems with frost heaving in the winter. The best places to use steel edging are where a great deal of side-strength is required, such as driveway work. Aluminum edging is easier to work with, but the silver color appears unnatural many landscapes.
Brick, stone, and concrete make useful and decorative edging. Be sure the brick or pavers are well fired so they are waterproof. Stone should be at least 3 inches think and at least 4 inches wide to stop the grass. A sand or concrete base, containing reinforcing rods, provides added durability and strength. The newer continuous concrete edging, poured by special machines, is becoming popular and resists cracking due to the addition of polyolefin fibers.
Wood edging provides a beautiful natural look. Landscape timbers, ties, and treated 2x4s are readily available. These stay in place well and create a nice mowing edge. Rebars and toe nailed corners provide added reinforcement. Avoid using old railroad ties coated with materials that are toxic to plants.
The most common edging used by homeowners is plastic since it is inexpensive and easy to install. Unfortunately, plastic edging has poor durability and an artificial appearance. Ferree says that of all the materials used as edging, plastic is probably the hardest to install for a lasting stable edging material. "Many of you have probably experienced the frustration of plastic edging that simply will not stay in the ground." Experts generally agree that round-top edgings are better since they do not sink as easily as flat types. If the flat plastic types are used, nail (using galvanized nails) a 1 x 1" strip of treated wood along the bottom of each strip where possible, to help stabilize the plastic. Most frost heaving can be stopped by using grooved or lip-style edging, steel anchoring stakes, and proper installation procedures.
Consider putting in a new edge on your landscape beds this fall. For more information on this or other horticultural issues, contact your local Extension office by visiting www.extension.illinois.edu. You can also post questions on Rhonda's facebook page at www.facebook.com/ILRiverHort.