Hey Wild Bill, Winter isnt too cold here, so the compost may be able keep its heat, thats a good idea so your compost was in the vege garden, the tomatoes probablty tried to get their roots into the compost lol. I am over this time release nutrient pottng mixes.You don't need to make a compost bin. I've never built one. The closest thing to a "bin" I've ever had was a pile of finished compost put in T-Post and chicken wire container and planted tomatoes around it. LOL!
If you don't make much, a tumbler type composter makes it pretty quick. You can still compost in the winter if it's not super fridgid and you turn daily to keep the heat and composting running. Composting on the ground in winter demands large volumes to help retain the heat and microbial activity running.