Savvy gardeners swear by heavy-duty, molded plastic for shaping neat edges of beds. Available from garden centers, nurseries, and mail order suppliers in rolls of flat, 4- to 6-inch-tall plastic, the edging installs easily. Using this edging, you'll save yourself from countless hours spent removing the grass and weeds that would otherwise creep into your beds.
2. Install plastic edging: Cut the edging to fit the dimensions of your bed, working in small sections. Be sure to buy high-quality edging; the cheap stuff tends to fall apart after a few years. Press the edging into place. Push soil in around both sides of the edging, allowing the top of it to extend 1 inch above the soil so it prevents runoff of water and soil.