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Greenhouse Heating

I have a bit of a dilema as I have seedlings in the greenhouse (glass) and our weather has taken a turn for the worse (snow) here in Brittany. I've bubblewrapped the stands that the seedlings are on and have kept a large chunky candle burning day and night. What I really want to know is whether I should stick to using candles to help keep the greenhouse frost free or whether I should invest in a paraffin heater (bearing in mind that paraffin in this country isn't cheap). I've researched about paraffin heaters and read other peoples reviews and quite alot of them are negative - soot deposits and smoke being the main problem. Not sure what to do and I really want to give the seedlings a good chance of survival. image



  • good morning Garden-Girl, would it not be wiser to wait for spring to arrive before you sow your seeds ?, is it possible to buy methylated spirit or kerosene .



  • can you not move them onto window sills for a week or so til the weather gets better? I wouldn't leave a candle unattended ever, most common cause of fires in the home, and especially if you have loads of bubble wrap about.

  • sotongeoffsotongeoff Posts: 9,802

    I am with Derek on this-you started too early-if you cant find a suitable spot for growing on then you fall at the first hurdle-sorryimage

    Really do not like the idea of a naked flame in the greenhouse-smacks of desperation tactics- sorry to be so brutal-put this down to experience and start again is my adviceimage

  • LynLyn Posts: 23,190

    Mine too Geoff.

    People are very eager to get started at the first sign of a good day, but frost can hit as late as April in a lot of places and you end up with plants big enough to go out, and cant put them out because of frost.

    Gardening on the wild, windy west side of Dartmoor. 

  • PalaisglidePalaisglide Posts: 3,414

    Garden Girl, I use an electric fan heater with a frost guard thermostat although not yet, experience has taught me it is way too soon to start seeds off, light is just as important as heat and there is not enough of it just yet.
    If you put your seedlings on the floor ( a few degrees warmer than on the staging) cover at night with fleece but take it off in the morning you may save them.
    Heating just the area you need quite small really with electricity if you have access to it is the cheapest way, that is how I do things now when I finally start to sow seed.
    Good luck and patience is the gardeners best friend.


  • Thank you everyone for all your advice. I am a novice gardener with a lot to learn!!!! I'm only sowing seeds because various seed packets and magazines tell you when you should!! Oh well, I guess I will learn from experience. image

  • PalaisglidePalaisglide Posts: 3,414

    Garden Girl seed packets are a general set of instructions, some one in the far South of the country would probably sow the seed around the time stated on the packet. As you go up country the time will vary by as much as a month so yes experience counts.
    France can change climate from one valley to the next, I notice tonight there is snow falling in the North of Spain so nowhere is safe, best leave things until you feel it is lighter and warmer and forget what it says on the packet.


  • Hi garden girl,I would try to save your seedling by putting a clear storage bin over them and at night cover with a wool blanket. That has keep my seedling warm and they are outside! It is cold here in n.y. Hope that will help . Ta Debra

  • Hi Gardengirl.

    I live in Scotland and have bad frosts.I close off a third of my greenhouse with bubblewrap and use one of those heater tubes(They cost the same as a lightbulb to run)Am a canny Scot lolimage.This seems to do the trick.

  • Gary HobsonGary Hobson Posts: 1,892

    The key to keeping anything warm is insulation.

    An eskimo igloo is heated purely by the body heat of its occupants. The eskimo don't have heaters of any kind. It can be -40C degrees outside, but it's as warm as +10C inside.

    A human being gives out about 100Watts of heat - only as much as a small lightbulb. But a couple of people is enough to keep an igloo warm. An individual human being in an efficient sleeping bag can easily remain warm in sub-zero conditions.

    So in terms of keeping a greenhouse warm, it's essential to elimate any draughts, and maybe use more than one layer of bubblewrap. Though additional layers of bubble wrap will reduce the light, which is important for seedlings. And it's easier to keep a small volume warm than a large volume.

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