Tomatoes grow better and produce more when using plastic as a ground covering than on bare soil, according to the Mississippi State University Extension Service. Plastic warms the soil, promotes rapid growth, controls weeds, acts as a barrier to disease organisms and allows for an earlier and cleaner tomato harvest. Most gardeners use black plastic mulch, which comes in various widths and lengths. MSU recommends a thickness of 1 ½ mils or 0.0015 inches.
Prepare the soil before applying plastic. Remove weeds and debris. Break up clods of soil. Rake in fertilizer and lime.
Rake the soil to make it smooth.
Lay down soaker hoses in areas prone to prolonged dry periods.
Bury one end of the plastic mulch in the end of the garden row. Unroll the plastic to the other end of the row, keeping it as straight as possible and pressing it down to contact the soil. Bury the edges as well. Alternatively, staple the mulch to the edges of a raised bed or hold it down with bricks or rocks.
Cut X-shaped planting holes in the mulch to insert transplanted tomato plants.