Garden edging ranges from a simple trench cut between a landscaping bed and your yard to a hardscape barrier made of plastic, metal or cement that blocks weeds and grass runners from reaching from your yard. Although you can purchase garden edging in lawn and hardware stores, you can create your own edging by casting concrete into a form that you design yourself.
Wet fine sand until it sticks together.
Shovel sand into a large box.
Sculpt a depression into the sand in the desired shape for your garden edging. A popular shape is a rectangle 2 inches wide, 2 feet long and 12 inches deep. You can also create a scalloped surface along the top of your edging, or make your edging resemble bricks or river stones.
Line the depression in the sand with a plastic dry-cleaning bag.
Mix concrete and water in a bucket with a plastic stirring rod. Mix until the concrete is the consistency of cake batter. If you wish to add concrete dye, now is the time.
Pour the concrete into the depression in the sand. Sprinkle with a spray bottle filled with water. At this point you can add additional decorations (by using leaves, marbles or other decorations in the mold).
Cover the concrete with plastic and allow it to cure up to 72 hours. If temperatures outdoors are cooler than 50 degrees Fahrenheit, the concrete will take twice as long to cure.
Carefully pull the concrete edging block out of the mold. The concrete will still be brittle at this time. Scrape away any rough edges with a copper wire brush. Allow the concrete to dry another week before using in your garden.