Cold Frame

A cold frame is an extension of a greenhouse allowing an intermediate step between the pots in the greenhouse and planting in the soil.  It is the place for the plants to harden before planting in hopes to reduce transplant shock.  

Materials used

1. 1x8x8 pine board

2. short pieces of lath

3. 5-24x44/1.4" clear single layer greenhouse polycarbonate sheets

4. A few nails and screws

I had to buy the 1x8 board but polycarbonate sheets and lath were given to me as scrap from another project.  

Assembling 

The trays I use in the green house measure 12x24".  The end 2" and the top bracing 1" boards were ripped from the 1x8 board.  The 2" board was cut into 4-24" and 4-20.5" boards to match a half sheet of the polycarbonate sheet.  The boards were tacked together.  The polycarbonate sheets were attached to the frame with small nails using a lath strip to hold it in place.   The lath were positioned to overlap the edge about 3/4".    The bracing boards were cut into 2-40" sections.  Short pieces of metal straps were used to attach it to the frame ends.  

The ends were attached to a solid base.  

Testing

We had a sunny spring day (4/20) where air temp was 55.  Soil temp at 3" was 82.