To make black plastic sheeting even more effective as a mulch in your vegetable garden, paint it with a coat of aluminium paint. This shiny coating reflects sunlight away from the soil and onto the plants' foliage. It keeps the soil as much as 3°C/6°F cooler, even in the heat of the summer, and promotes stronger growth. (In trials, it has increased the yield of marrow plants by 60 per cent.) It also repels aphids and thrips.
A coat of red paint has a similar effect on tomatoes, boosting their yield by up to 20 per cent over plants covered with ordinary black plastic. White plastic is good for potatoes and sweet peppers, while green plastic is best for early spring crops.
