How can I keep my plastic greenhouse warm in the winter?
INSULATION The most effective method is to use bubble wrap polythene, cut to size and fixed on the inside of the Greenhouse, close to the glass. This is a fiddly task, since the material has to be cut to fit, and it may take more than one person to install the insulation. Bubble wrap insulation: cheap, effective, underrated Single-pane glass loses heat fast. On a still winter night, a single-glazed greenhouse can lose 80% of its stored heat within a few hours. Horticultural bubble wrap is the cheapest fix.