JoAnn, I'm a rookie myself, but bedsheets work. We're going through this right now, too. 81 degrees on Tuesday, below freezing Wednesday night.
I bought some 2' bamboo stakes at my local Lowe's store (about $3 for a package of 25 or so), put a stake on either side of my plants. Then draped bedsheets across the bed with rocks/bricks holding the edges down, proped on the bamboo stakes to keep the sheet off the plants as much as possible.
Here's a recent similar thread:
//www.agardenersforum.com/forum/ubbthreads.php/ubb/showflat/Number/9782/page/1#Post9782
Hope it helps,
David
Last edited by weezie13; Apr 11th, 2007 at 04:10 PM. Reason: Shortened the URL