Talkback: Greenhouse heating

Posts

• Gardeners' World Web User Posts: 17,147

  January 2010

  I am sure there is a way a solar heating system* could be modified for a green house. The joy is they get hot inside the insulated tube even on cold days from solar radiation, the catch is it would need to be hooked up to some sort of a big heat sink under the greenhouse. (Added benefit of heating the soil at the roots.) They did a DIY version with hot air on "Its not easy being green", and on another show some people made a diy solar heating system form blackened copper pipes. Does anyone with experience of these technologies think it might work / be cost effective? I would love to know but wont be able to try it out myself for some years yet.
  *not photo elec pannels but the ones that heat a tube of water inside an insulated glass tube.

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• Gardeners' World Web User Posts: 17,147

  January 2010

  I grew tomatoes aubergines and peppers in an unheated greenhouse last year. I started them off in a propagator in the house, then onto a window sill and only outside when the weather had warmed up. A later crop but no problems with fretting over the heating/environment debate.

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• Gardeners' World Web User Posts: 17,147

  January 2010

  I find the big chunky candles from pound shops useful to keep an 8' x 6' greenhouse frost free .If you place one in a terracotta pot and invert another on top with a piece of broken crock over the drainage hole in the top pot.The broken crock still has to allow ventilation,but the heat generated will surprise you and chunky candles will last for several nights.

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• Gardeners' World Web User Posts: 17,147

  January 2010

  To reduce the cost of heating a greehouse it is necessary to reduce the area you are heating by using bubble wrap. The shelving area can be confined and a simple frame work erected to pin the b'wrap to. I use an elect. fan heater with thermostat and the cost is is kept to a bearable level.

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• Gardeners' World Web User Posts: 17,147

  January 2010

  My greenhouse if full to bursting with cacti, pelargoniums - both zonal and regal - fuchsias and other frost tender plants, plus quite a lot of of cuttings of fuchsias, pelargoniums and perennial plants.
  
  I use a thermostatically controlled electric heater to keep my greenhouse at a suitable temperature to overwinter them but one day last week we had a power cut in the early hours of the morning and the greenhouse temperature dropped very low. The result is that the leaves on some plants are showing signs of being hit by the cold, I think I will be able to save them but it will be very disappointing to lose them having brought them this far through the winter.
  I certainly don't have room to put candles in the greenhouse as there is barely room to fit another plant in! Also, candles pose a serious risk of fire.

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• Gardeners' World Web User Posts: 17,147

  January 2010

  Thanks for all your interesting comments and observations.
  
  Electric fan heaters are very efficient, as they are thermostatically controlled. The fan also circulates air to avoid hot and cold spots.
  
  Insulation is also very important, and you can use sheets of bubble polythene as curtains to divide up a large greenhouse into smaller areas, such as over the staging. Then you can just heat inside this smaller area rather than having teh expense of heating teh whole greenhouse.

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• Gardeners' World Web User Posts: 17,147

  February 2010

  I've found platic drinks bottles filled with water and wrapped in black polythene or bin liners quite effective among tender plants. I've also been surprised at how many tender plants have survived by keeping them dry and draping newspaper over them on the coldest nights, when the temperature went down to -6. hey're not always happy, but they're alive and will picj up later. My Melianthus has lost its leaves but the stems are ok. I ave bubble wrap round the pot and a cardboard box over the top growth. Not pretty, but it works!

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• Gardeners' World Web User Posts: 17,147

  February 2010

  Thanks to mjohn345 for his tip on heating a greenhouse with two terracotta pots and chunky candles. Tried this and it works a treat! Plenty of heat generated to keep the frost off and no more worrying about whether I will get up one morning to find my greenhouse covered with black oily soot from a paraffin heater. Pots from Wilkinson £1 each, candles from pound shop £1 each which I think will last a good while.

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• Gardeners' World Web User Posts: 17,147

  February 2010

  My greenhouse is 8x6 feet.I built a frame 4 feet from the door and covered it with bubble wrap. I heat this area with two terracotta pots and a large candle placed in one of the pots and the other pot inverted and placed on top.It saves on the price of buying paraffin and a lot cleaner

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• Gardeners' World Web User Posts: 17,147

  March 2010

  My greenhouse is bursting with cuttings of pelargoniums, zonal and angel, margarites, etc. and now I've sown many seeds of various veg and flowers. My greenhouse is heated with an electric fan heater but with night temperatures here at -4 I have to make sure the temp stays stable. My husband is not a gardener and he checks out the heater output. What he hasn't realised is that now my propagator is on with seed sowings, I am using more electricity!! He is happy to eat my veg and enjoy my flowers though!

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