Greenhouse frost protection

Hi All

I seem to remember hearing, many years ago,  that burning a night light in a garage generated enough heat to ensure the car started first time even after a frosty night.  I think I recall that you put the night light on the garage floor and covered it with a clay plant pot.

I was wondering if anyone can remember this tip or had even tried it.  If so could it be used in a greenhouse?

thanks
Dragonfly

hi , we in darkest yorkshire line our greenhouses with bubble wrap, hold it in place with alliplugs , works for us, greenhouse startys up at least 5 degrees above  freezing and keeps going ,

You could wire a low wattage bulb in to the pot if you have mains to the greenhouse saves the candle going out