Some cheap and eco friendly ways to heat a winter greenhouse
The cost of heating a greenhouse in winter can outweigh the savings and advantages of growing produce in one.
Greenhouses are poorly insulated, but by making a few improvements to insulation and trying some of the heating methods here, you could reduce the cost of heating a greenhouse in winter.
Stuff you can use to insulate and heat a greenhouse in cold weather,
Rabbit hutch, Paraffin, Straw, Cardboard, Bubble rap, Decomposting Hay or Straw bales, Dust bin or old oil drum
Greenhouse Paraffin heater.
Paraffin heating is the simplest way to heat a greenhouse up to about a maximum length of 8ft in a relatively mild winter
If heating demand is not to high through Winter and outside temperature does not fall below -6C and the required greenhouse temperature is no more than +5C, one paraffin heater will keep your greenhouse free of frost and should run for 24hrs a day for up to about three days with a single fill.
All greenhouse paraffin heaters vary so best to check the instructions.
If you use a greenhouse heater you can help keep greenhouse heating costs down and still grow plants through late Autumn and Winter months by adding a layer of bubble wrap to insulate your greenhouse.
Cutting Greenhouse heating costs tips
keeping your greenhouse glass or plastic clean, especially the overlaps and siting your greenhouse in a bright spot that gets sun all day allows more sunlight in. lean-to greenhouses benefit from the heat lost through the walls of your house so make the most of free greenhouse heating. Greenhouses built on a brick or wood base hold onto heat better and all glass greenhouses can be insulated by leaning cardboard or straw bales against the bottom panes. Sealing gaps around loose panes and doors also help stop heat escaping.
Found this Idea for a small greenhouse heater using a nightlight, a saucer and a terra-cotta pot, on a forum. Usually a night light lasts eight hours so I’m going to experiment with these in saucers beneath a metal bucket and on a saucer in an old watering can.
Bubble wrap greenhouse insulation
Even If you are not using a greenhouse heater, insulating your greenhouse with bubble wrap will widen the range of plants you will be able to grow through winter. Its easy and cheap to insulating a small greenhouse with bubble wrap and only takes about an hour.
Plastic clips can be bought to hold the wrap in place,or try using clothes pegs, remember to fasten the bubble wrap around windows, doors and vents in away that they can still be opened.
Mini plastic greenhouse.
If you cant be bothered to bubble wrap your greenhouse but still want to grow plants in Winter try placing a cheap mini plastic greenhouses inside the glass greenhouse.
Placing a Rabbit hutch in your greenhouse will help heat it up.
Another way, if you have a pet rabbit, is to place the hut inside the greenhouse, the heat it radiates will take the chill of the air. Your rabbit might like it too.
Decomposting Hay or Straw bales will heat up a greenhouse in winter.
If you have enough floor space, try composting a bale, a composting bale gives off heat. You can also plant and grow stuff in the bale, so space may not be a problem for you. More information on this page hay bale garden
Dust bin or old oil drum, filled with water saves greenhouse heating costs.
Place a dust bin or old oil drum, inside your greenhouse and fill it with water. Water has a high specific heat (amount of energy needed to raise the temperature by one degree) and will absorb excess heat keeping the temperature down in the summer. The high specific heat of water will also allow it to hold onto the heat in winter and keep your greenhouse a few degrees warmer in the winter. Haven't tried this but it sounds as if it should work, let me know if you try it.
Plants to sow and grow in a greenhouse in Autumn and Winter
If you are not planting and growing through the winter but just heating the whole greenhouse for a few less hardy plants, you might want to think about moving them into your house for the winter months.