Wood, in the form of landscape timbers and railroad ties, can effectively define a straight-edged bed but is nearly useless when it comes to curves. And don’t forget that railroad ties contain creosote, which will leach into the soil and contaminate plants. Landscape timbers can be cut in shorter lengths and installed vertically to handle curves. Because most wood rots, you will need pressure-treated landscape timber or wood that doesn’t readily break down.
Although metal edging is a material that is more expensive, it is often the choice of professionals. It can be used in curved beds or bent to 90-degree angles for a linear landscape. Metal lasts nearly forever and will blend into the landscape if installed properly.
Though it is more cost effective than most of its counterparts, plastic edging lacks aesthetic value; it is often noticeable in a landscape and can appear tacky. Plastic often works its way out of the ground during freeze-and-thaw cycles, and it is easily damaged by a mower’s passing blade. Stone, brick, and concrete will last nearly forever, but they are not good alternatives when cost is a factor. And if they are not mortared together, sneaky grass and weeds will find a home between each piece. They can also wreak havoc on mower blades. Your best bet is the natural or Victorian edge, also referred to as a Victorian trench. This is the most cost-effective edge available, requiring only time and elbow grease. To attain this edge, use a sharp spade to make a vertical cut in the turf at the edge of a bed. Remove soil to a depth of 3 to 4 inches, at a 45-degree angle to the freshly cut vertical edge. With a rake, smooth the soil to slope toward the border plants; this creates a beveled cut. Smooth out the remaining soil. If need be, you could rent a bed trencher for a day or hire a local landscaping company to create a trench for you.
To maintain a clean line, the beds should be retrenched in spring or as needed. A Victorian edge will blend into any landscape and is as effective as any product for providing a barrier to grass and weeds and for containing mulch.