The color of a mulch largely determines its energy-radiating behavior and its influence on the microclimate around a vegetable plant.
Color affects the surface temperature of the mulch and the underlying soil temperature.
The degree on contact between the mulch and soil, often quantified as a thermal contact resistance, can affect greatly the performance of a mulch. If an air space is created between the plastic mulch and the soil by a rough soil surface, soil warming can be less effective than would be expected from a particular mulch. Black plastic mulch , the predominate color used in vegetable production is an opaque blackbody absorber and radiator. Much of the solar energy absorbed by black plastic mulch is lost to the atmosphere through radiation and forced convection. The efficiency with which black mulch increases soil temperature can be improved by optimizing conditions for transferring heat from the mulch to the soil.