While looking for varieties of grow bags available for above ground gardening, I ran across a video on You Tube posted by a gentlemen from Georgia that has grown more than 100 pounds of watermelons from a single bag of compost. One of the melons even grew to 28 pounds. He plants watermelon directly into the bag.
Here's a video demonstration:
I'm going to try a bag for watermelon and a bag for canteloupe this.