USDA and university researchers have found that red mulch enhances the growth and yield of several vegetable crops, including tomatoes. The color of the mulch changes the intensity of certain wavelengths of light, and the modified light increases plant growth and yields.
 
Red mulch reflects intensified red light to developing plants, which increases their photosynthetic capacity. Leaf cover is reduced early in the season, so more of the mulch is exposed to light, and more light is reflected to the plants. 
 
Advantages 
Uniform red color for uniform field results.
Soil warming of 4 - 6° F.
Almost total weed control.
Reduction of soil moisture evaporation.
Conservation of soil nutrients especially nitrogen.
Improved yields in trials.