I don't know about sand. I mean I'm not saying the other dude is wrong, but I feel like I read something bad about sand. I recently used lots of perlite mixed with good organic soil/compost and some worm castings. I also threw in some bone meal because we use it on other plants on the farm. The strawberries we planted got HUGE with just a little bone meal under the soil right below the roots but not actually touching the roots. So ya just my 2 cents. I don't think you can go wrong with good stuff like perlite, compost, worm castings, etc.