Cold frame plans are fairly easy to implement. A cold frame is essentially a bottomless box around 1 foot high with a hinged glass lid. The box is either positioned on the ground or sunk into the soil a couple of inches. How big the box is conditional upon the gardener and how many plants they wish to fit inside of it. If you are planning to relocate the box, you should put handles on both sides of it.
The box should be taller in the back and lower in the front side. This sloped design is so that an increased amount of sunlight can get inside of the box when facing the lower end towards the sun's rays. Needless to say, the lid also needs to open in the front.
Several diyers implement their cold frame plans by hinging old window panes onto wooden frames. For the best results, polycarbonate is highly recommended as it will not shatter or break in a way that is often dangerous for those who may happen upon it by accident like children or pets. The best wood for this project is cedar or cypress that has been treated with a non-toxic preservative. You can also paint the wood to make it be preserved longer.
It is important for the lid to be adjustable for ventilation purposes. You'll want to place a thermometer inside of your cold frame so that you will see when it should be ventilated. Ventilation should occur anytime the temperature rises over 75 degrees fahrenheit.
If you take heed of these guidelines then you really cannot go wrong. Without doubt, you'll have a beautifully temperature controlled garden growing before you know it.