Red plastic mulch was developed by the US Dept. of Agriculture and Clemson University for the purpose of increasing yields for commercial growers. It is proven to increase yields by roughly 20% . When properly used, red plastic mulch for Tomatoes not only increases the overall yield – it also increases the size of the individual tomatoes, and it is speculated by some that the tomatoes produced are of a higher quality , more flavorful.
Like all mulch, red plastic mulch warms the soil, which in effect extends the growing season slightly. Also like other types of mulch it enhances moisture retention in the soil and prevents erosion. The added benefit to using Red plastic mulch as opposed to traditional varieties of plastic mulch is in its ability to coax the tomato plant into a higher level of fruit production.
It coaxes increased tomato production by reflecting back the red spectrum of light at the plants foliage. Phytochromes, which are basically pigments within the plant, are color sensitive and one of their functions is to help regulate growth and development of the plant and its fruits.
When red light wavelengths from the plastic are reflected onto the plant the phyochromes are basically tricked into behaving as if the season is ending in the near future.
Grown naturally they would be receiving red light waves from ripening tomatoes – receiving these ‘signals’ earlier they are mobilized into ripening and producing more fruit at break neck speed – which is what nature has programmed them to do.
Eggplants also respond better to the use of Red Plastic Mulch, not as much as their Solanaceous cousins the Tomato and pepper clans, they only show a 12% increase in yield at best, as opposed to 20% for Tomatoes. Peppers as per a Penn State Study did not show any dramatic increase when grown with Red Plastic Mulch, however – they responded favorably to silver mulch when compared to black with an average 20% increase in fruit yield and size.
Red Plastic Mulch is not only beneficial in tomato production, it has also been proven highly effective in increasing strawberry yields. “Yields over the red plastic (SRM-Red) were compared with those over standard black plastic in field experiments at a research center and on a commercial strawberry farm. Yield per plant and size per berry were greater over the red than over the black plastic at both locations.” See – Strawberry Yield over Red versus Black Plastic Mulch American Society of Agronomy
Red Plastic Mulch has also been shown to be the best for Watermelons. See: Influence of Preharvest Factors in Melon Fruit Quality
Cantaloupe and closely related musk type melons are an exception – Red Mulch does not appear to have the same effect on them – however “this crop appears to respond more to green IRT or dark blue mulch compared to black with an average 35% increase in marketable fruit …. Lowest yield of marketable cantaloupe were harvested from plants grown on either white or black mulch at this location. Summary and Recommendations for the Use of Mulch Color in Vegetable Production Penn State Extension.