After reading MR’s thoughts on using black plastic mulch for growing squash – Ijust read this on Maria Rodale’s site: (what does anyone think?)….
Black and red plastic mulches come in rolls and can be laid down to suppress weeds; they’re particularly useful when growing warmth-loving tomatoes and eggplants because they warm the soil underneath. However, these mulches are not a very sustainable option. Plastic comes from petroleum, and more and more research finds that when it’s heated (say, in the sun), chemicals leach out of the plastic. We recommend organic garden mulches because they add to soil fertility.
I think Margaret would agree with the statement from Maria Rodale’s site. To use the plastic sheeting to grow squash (or watermelon, sweet potatoes and other hot soil loving crops in cooler summers), the sheeting is laid down early to heat up the soil and then removed- this way it can be re-used for multiple years and also does not prevent rain water from getting to the squash once they are actually growing. Check out the mulch faq’s for more details on mulch. Plastic sheeting is the 8th question down.
When I was growing up, my mother used plastic sheeting all season long and I always hated the way it would eventually disintegrate into many really annoying little pieces. For environmental reasons, I would like to say that I have never used plastic sheeting, but in my own garden I have used it to heat the soil early in the season for both watermelons and sweet potatoes. Unfortunately, I’m not sure I would get a decent crop with out it.