For reasons still somewhat unclear, certain colors can help stimulate the growth of tomatoes… and that includes the color red. It is believed that this effect comes from the color reflecting a specific spectrum of light to the plant, which in turn triggers photosynthesis… and of course, photosynthesis boosts growth, increases yields, and stimulates faster maturation. So if you spread the red plastic mulch under tomato plants, they’ll grow better with more numerous fruits that will ripen faster than those of tomatoes grown in bare soil.
Of course, part of this effect comes from the fact that plastic mulch of any color warms the soil and therefore also stimulates faster growth, especially in cool climates. Still, red plastic mulch gives better results than black plastic mulch or transparent mulch.
Red plastic mulch has also been tested with success on other fruit-bearing vegetables: melons, peppers, squash, cucumbers, etc., even strawberries (which aren’t vegetables, after all). All bear more, better and earlier with a red plastic mulch, at least when compared to bare soil. In increase in yield of 20% is often stated… although that depends on local conditions.
What? Red is just not your color? In that case, more recent studies show that the blue plastic mulch is even more effective than red plastic mulch. However, it is difficult to find blue plastic mulch on the market. Harris Seeds is one of the rare places that does offer it.