Heating a greenhouse is critical in the cooler months where the lower temperatures will usually stunt the growth of the plants if not kill them. In other words, without a heater, there is almost no point in having a greenhouse. Using kerosene is an affordable way to heat the area. Of course, there are many heaters out there on the market, but there is a way to make your own for just a few dollars.
Buy a simple broodhouse heater from an online source or antique shop. These little heaters were used to heat hen houses during the winter and can put off quite a bit of heat. They hold about a quart of kerosene, which will probably last you a couple of nights. The heater should have a 1-1/2 to 2-inch wick opening and maybe even a double-wick assembly.
Cut the top and bottom off of a 907gr metal can such as the kind found filled with beans. Remove the label and clean the glue off the can. It should not have any plastic liners. Set it on top of the heater and make sure it fits on the top of it squarely inside the metal pegs used to hold the glass chimney. Turn the metal in a little if necessary to fit the opening.
Install the new wick by unscrewing the top assembly and feeding it into the burner assembly from the bottom. Fill the reservoir with kerosene and allow it to sit so the wick can soak up the kerosene. Close the assembly and set the heater outside on a flat surface.
Light the wick by turning it up high enough so your match can reach it. It will be smoky at first. Turn down the wick until you have a clear, level-coloured flame of mostly blue. Set the can on top to serve as your chimney. Turn the flame up a little and let the chimney heat up and the smoke should dissipate as the air flow gets established.
Bring the kerosene heater into the greenhouse, being careful not to touch the chimney. Set it in a safe area away from warming any plants by radiating heat. Keep the air circulating in the greenhouse by using a small fan; make sure to keep a window open somewhere to keep good ventilation. You do not want the condensation given off by the heater to collect on the plants.
Keep the wick trimmed after use for a cleaner flame