Growing during the heat of summer, tomatoes can lose out to weeds in a competition for water and nutrients. By putting down a mulch in the tomato patch, you'll reduce the growth of weeds and remove the competition. The mulch will also keep the soil evenly moist, which tomatoes also love, and they will reward you with an abundant crop.
Performing well overall, wood chips effectively control weeds and retain moisture in the soil. This results in healthy, productive plants that are less susceptible to pests and disease. Put down a 3- to 6-inch layer of wood chips for the most effective weed control. Pull them away from the main stem of the plant so the wood chips do not touch it, to keep slugs from taking up residence there. Many large cities provide wood chips culled from their urban forests free for the taking.
Free from your own lawn, grass clippings are an excellent mulch for tomatoes. Although it will take several mowings of an average-sized urban yard to collect enough clippings for an 8-by-8 foot garden plot, they should be laid down to a depth of at least 2 inches. At this depth they will control weeds very well and keep the soil evenly moist.
Widely used by home gardeners, black plastic mulch is very effective in moderating the soil temperature and stopping the growth of weeds. Because it is impermeable, water can form puddles on the surface and can only enter the soil through the planting hole near the base of the plants. Tomato plants grow well under black plastic mulch, but may not produce an abundance of tomatoes, according to the University of North Dakota Extension.
Hay or Straw
Available at larger garden supply centers, hay or straw makes a very efficient mulch for tomato plants. Their golden color reflects sunlight, which gives the tomatoes an added growth boost. Put down at least a 4-inch layer of hay or straw to keep soil temperatures cool and greatly reduce weeds. Any weeds that do grow through this mulch will be weak and easily pulled out. At the end of the growing season, turn over the top layer of soil, incorporating the straw, after removing the spent tomato plants. The mulch will further decompose over the winter months and improve the soil in your vegetable bed.