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Greenhouse winter heating

Can I use an oil filled radiator to heat my 6x6 polycarbonate greenhouse to raise seeds from January onwards?
Has any one used one?


  • cornellycornelly Posts: 968
    What size is the heater and how would the electrics be connected ?.
  • NollieNollie Girona, Catalunya, Northen Spain.Posts: 6,551
    I used to have oil-filled radiators in a flat I rented yonks ago, they were extortionately expensive to run! Might not be the most cost effective way of heating your greenhouse. Perhaps a couple of electric heated mats under the plant trays/covered propagators would provide more direct, controllable heat where its needed, more cost effectively?
  • Pete.8Pete.8 Billericay, EssexPosts: 9,872
    What sort of seeds are you thinking of sowing in January?
    A heated propagator may be a better option.

    The main consideration though is the lack of decent natural light in the early months of the year if you're in the UK. It's not too difficult to germinate seeds in Jan with some warmth, but providing enough light for them to grow properly needs to be considered too.
    I've germinated tomato seeds in Jan but by March the plants were so leggy they were useless. I now sow them in a heated propagator the first week in March every year and pick my first toms in late June.
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • ObelixxObelixx Vendée, Western FrancePosts: 28,574
    You'd need to insulate it with bubble wrap to make it less costly and that will further reduce light levels.  Much better to wait till March when light levels are better and seedlings can grow short and sturdy rather than thin and etiolated.

    As said above, a heated mat or a temperature controlled propagtor would be more efficient and can be varied according to the seeds.  Some like it warmer than others so it depends on what you're planning to swo and where you are.   

    It's pointless getting too far ahead with anything but the hardier plants as tender plants need potting on and on again and watering and feeding and hardening off in coldframes before they can be planted out after tha last frosts of May.  6 x 6 may well be a squeeze for all that.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • LynLyn DevonPosts: 21,144
    I sow most of my seeds in March going onto June, never had a propagator, prefer to use mother Nature’s own,
    If you sow seeds at the correct time there’s no need for heating. Mine are put on a work top in the kitchen and some on a spare room table. 
    Gardening on the wild, windy west side of Dartmoor. 

  • Thanks all o have 2 greenhouses 22 hanging baskets so I need to start early will look at mats maybe a Xmas idea
  • fidgetbonesfidgetbones Derbyshire but with a Nottinghamshire postcode. Posts: 16,472
    I use an electric fan heater plugged through a separate thermostat.It keeps within a narrow range.  My mum has same plus uses a heated mat to start seedlings early.
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