@Weedwhacker,
I used Miraclegrow Garden Soil. I don't think it's supposed to be used for containers but it's what I had. It has a lot of compost in it. I probably should have mixed some potting soil in with it but I didn't have any at the time. The plants were given to me so I thought I'd give growing squash a try. I've never grown anything other than flowers (and a couple of mango and apple trees I started from seeds but they died). I've heard squash is pretty easy to grow. I'm a gardening newbie so I've got a lot to learn. I'll get it figured out though