Here is a link that recommends putting black plastic under watermelon plants for increased production.

http://www.urbanext.uiuc.edu/veggies/watermelon1.html

well my experience with this was that the vines did not burn up but the fruit did not seem to set very often on the flowers on the black plastic, the vines that travelled off the plastic set lots of fruit, I had great success last year growing on black landscape fabric, it doesn't get that same heat as plastic and lets moisture through, i have also had good luck growing on cardboard as a mulch, i would recomend putting something on the plastic, some boards, cardboard or straw( although that can be a home for pests), squash on

Agree with thefarmguy - cover it with mulch. The black mulches can ofter overheat the soil and so the roots under it. Results in plant stress and reduced production. It all depends on your climate. Here with all the 95-100+ degree days unmulched black would definitely cook the vines.

I cover mine with hay as it is free vs. buying straw. But either will work well. That way you get the best of all worlds, no weeds, protected fruit, and cool stress-free plants. ;)

Dave

I grow just about everything, including squash and melons, on black woven polypropylene weed barrier, leaving a 4" slit between 4 foot wide strips. While the actual stuff may get too hot to touch, it actually works as an insulator for the underlying soil temperature, and that effect is increased by putting mulch over the plastic.

It's counter-intuitive, for sure, but I've checked it with remote thermometers. So I have a lot of cool season crops, like peas, fava beans, spinach, and so on growing between blazing hot black weed barrier, and they love it.

That said, I grow in a high desert, where the humidity most of the summer is

I think I will use cardboard and just lay it down as the vines progress, that would be the cheapest way. Would the moist cardboard have a negative affect on the vines?

Dale

I'd worry about the wind blowing away the cardboard, and taking part of the vine with it, but a couple rocks or something would take care of that. I'd also lift up a melon now and again and see if there is any effect on the fruit - sometimes that happens if what ever material the fruit is resting on doesn't dry out. But sounds like a good idea.