|Winter starts next week so I have dragged out my cold frame to protect sowings of winter and spring vegetables.|
I keep the cold frame flat-packed in my smaller shed during the warmer months, and before I assemble it for winter, I clean it and give it a new coat of paint.
The walls are made from 9mm marine plywood so they don't rot, but the front and rear walls are reinforced with untreated pine, so they need plenty of paint. The glass top is recycled 6.38mm laminated sheet. The floor is double walled insulated black plastic (just laid on the ground), and there is a strip on the back wall. These absorb sunlight and provide good radiant heat during the day. They also help to insulate against heat loss during the night.
There are two vents one in each side wall. They are just circular pieces of marine ply, covering a hole drilled in the wall. They can be swung open when ventilation is needed. If it gets too hot, I use a small piece of timber to open the glass lid a little to provide extra ventilation (as shown above).
I have been using it for 4 years, and it works very well.