The growing season is back with us and I've decided to modify the cold frame I built last year to make it more suitable for bringing on seedlings.
I wanted to insulate the cold frame against the frosts that are still about from now through to late April.
I bought: -
- A 2.4mx0.6m sheet of 50mm thick polystyrene insulation board (£6 at Wickes)
- Some heavy duty kitchen foil (about 20 pence worth)
- A Parasene 79864 paraffin cold frame heater (£21 including 4 litres of paraffin)
The first thing I did was line the inner walls of the cold frame with the kitchen foil.
Then, using a saw for longer cuts and a bread knife to shape any rough edges, I cut sections of the polystyrene insulation foam to line the walls of the cold frame. I cut other sections to line the floor of the cold frame and the offcuts have been shaped to place over the glass lid at night (with a board weighing them down).
The whole process of insulating the cold frame took about 20 to 30 minutes.
The paraffin heater is in the cold frame on a very low light. It's quite mild today and the sun is shining- the outside temperature is about 10C. The temperature in the cold frame is currently 26C.
Of course, it's pretty easy for the frame to warm with the sun shining - I really need to test the minimum overnight temperature of my insulated cold frame to see if it will remain warm enough to resist frosts.
To that end I bought a min/max thermometer that will record the minimum overnight temperature in the newly insulated cold frame.