Black plastic mulch is most often used in cooler climates, where the growing season is too mild to allow certain plants to fully develop and produce fruit under normal circumstances. The plastic mulch increases the soil temperature by 3 to 5 degrees F, prevents weeds from growing, and decreases moisture loss in the garden bed, according to Fort Valley State University. Some crops that work well with black plastic mulch include tomatoes, squash, melons and eggplant.
Prepare the garden bed before you lay the black plastic mulch. Loosen the top 6 to 8 inches of soil with a hand tiller, removing rocks, stray roots, and other debris. Sprinkle a layer of fertilizer or compost on top of the soil and work it in with the tiller. Water the ground evenly to moisten the dirt.
Dig a 4- to 6-inch-deep trench along one side of the garden bed, using a shovel or hoe. Dig a similar trench along the opposite edge of the garden.
Unfurl the black plastic mulch slightly, creating about a 3-inch tail. Drop the tail into the trench and fill that section of the trench with dirt to firmly anchor the sheet of mulch.
Unroll the black plastic mulch across the garden bed, stopping when you reach the opposite trench. Cut the length of mulch away from the roll with a sharp knife, making sure to leave a 3-inch tail. Tuck the tail into the trench and cover it with dirt.
Repeat this process until the entire garden bed is covered, slightly overlapping the lengths of black plastic mulch.