Posted: 25/06/2014 at 15:11
Stop! Think carefully before you break up the concrete base. I have a raised bed lined with pond membrane in my greenhouse and I find it dries out pretty fast. If you are only there twice a week, who is going to water on the other five days? I water my tomatoes every day. They are in bottomless pots on a bed of fine stone/gravel.
Before you go breaking up the concrete, take as much advice as this forum can offer you. So far you have only had two views!