You can make a simple cold frame yourself without much effort.
As material for the forehead- and side walls, in addition to planks, concrete is also suitable- or other panels of the required dimensions. Strong posts or squared timber should be used for the corners of the cold frame. Prefabricated concrete columns are better and more durable, those with a suitably wide groove for inserting the forehead- and side walls are provided. The stakes or concrete pillars are embedded at least 30cm into the ground. In addition, slats are to be attached to the inside of the box walls for better support of the cold frame window. The windows can be prevented from slipping off by screwing short batten pieces to the southern end wall. Simple cold frames are set up in an east-west direction, Double boxes in north-south direction.