Last year, we bought special plant covers for freezes. Almost everything died. I called the company and they weren’t very sypathetic.
This year, we decided to use bed sheets, because last year, we covered a few things with bath towels, and they did great.
I went to a resale shop and purchased full sized sheets (they didn’t have anything larger). I got 3 flat sheets, 1 fitted sheet, and 2 pillow cases, as there was one complete set and 2 separate sheets. I washed them and hung them out to dry.
From the home and garden store, as instructed in the Square Foot Gardening book, I purchased 2 PVC pipes, 10 feet long, 1/2 inch in diameter. They had two types. I purchased the ones that bent the easiest. I put the ends in opposite corners of my garden box, thus forming a frame that I can drape a sheet over when it freezes. I also used string to tie the two PVC pipes together at the top.
My other garden boxes have either tomato frames or wire cages, so they didn’t need PVC pipe frames.