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Greenhouse heating

Celia47Celia47 Posts: 14
in Tools and techniques
This year I installed a lean-to greenhouse (east facing) attached to the back of my house. It has done well so far as it warms up during the morning and stays warm until nightfall. However, I want to get some seeds going over the winter and have been looking at heaters. Has anyone had any experience of the eco bar heaters? I really don't like the paraffin heaters.
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Posts

  • PosyPosy Posts: 3,601
    Do you have electricity in the greenhouse, Celia?
  • Pete.8Pete.8 Posts: 11,340
    I have a lean-to too
    I put a bar heater in. I'd say it mostly kept the greenhouse frost free over winter, but not always. It's only 60 watt I think, so just about ok to over-winter plants but not much more.
    So I bought one of these  - which does keep my greenhouse above freezing. It has a thermostat and is splash proof.
    If I was going to start seeds very early I'd use the propagator as well.
    The big problem with starting seeds early is getting enough decent light. So I rarely sow anything before March





    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • Celia47Celia47 Posts: 14
    Thank you for your replies. I will have electricity in the greenhouse. The bar heater I have been looking at was a Lighthouse eco heater 120w 1500mm. Do you insulate your greenhouse as well, Pete8?
  • Pete.8Pete.8 Posts: 11,340
    Hi Celia
    a 120W heater is about the equivalent heat of 2 light bulbs and I doubt that will keep your greenhouse much above freezing (assuming it's like mine 6ft x 2ft), but if we have a mild winter you may be ok. It depends on what you're trying to grow.
    I don't insulate the little greenhouse. It's very well sheltered and faces west.
    I don't sow anything until March at the earliest as the lack of light causes seedling to stretch too much.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • Kitty 2Kitty 2 Posts: 5,150
    Hi Celia 😊. What seeds are you aiming to grow?
    I start mine off in an east facing conservatory, but like Pete wait until March when light levels are better.

    If it's a bit of warmth to kickstart germination you want, have you considered a heated propagator?
  • PosyPosy Posts: 3,601
    I use a fan heater with an internal thermostat. It keeps my half hardy perennials happy but I have given up on germinating seeds very early. I found they started well but I just couldn't justify the cost of keeping the greenhouse warm enough for them. Plug plants have the same problem. They sound like a bargain but you need so much warmth and light that it wasn't practical. I haven't had any problems with sewing a bit later.
  • ObelixxObelixx Posts: 30,090
    Unless you are sowing seeds that need winter stratification to break dormancy or sweet peas that can cope with winter chills anyway there's not much point sowing anything before March because, as stated, the light levels are too low.

    The exception would be tomatoes and chilies that some people start as soon as January and February but they do need extra light as well as warmth.
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • Celia47Celia47 Posts: 14
    Thanks for all of your comments. In which case, I'll probably just use it to over winter tender plants. If next year is anything like this year, with the big freeze early on, I'll still need the heater in March! Back to planting the spring bulbs for now then. Thanks again folks. 
  • hogweedhogweed Posts: 4,053
    I built a wooden box about 1m x .75m on the staging in my greenhouse. It is filled with sand and has a soil warming cable in it. Very cheap to run - I normally switch it on beg March and is great for seed sowing and plug plants. I make a tent over the top of it with fleece for the very cold nights. I'm not sure why soil warming cables are not more popular. It could be used over the winter for tender plants as well and very much cheaper than trying to heat a whole greenhouse. 
    'Optimism is the faith that leads to achievement' - Helen Keller
  • barry islandbarry island Posts: 1,847
    edited October 2018
    I constructed a seed starter box from a large 145L storage box, bought from homebase for £20 although I have seen them cheaper since, insulated internally with 25mm thick polystyrene sheets from wickes cost £6 which I covered with kitchen foil to reflect the light, i fitted one large and one small heated propagator in it without the lids, I already had these, then made a timber frame which sits on the top of the storage box, timber from free pallet wood, which carries two 10w vaxer grow lamps which I bought from Ikea for £10 each, I cut some polycarbonate sheet, which I already had from repairing my greenhouse, to sit in the box between the seedlings and the grow lights. Add to that a couple of other fixings and voila! I wondered if the two lamps would emit enough light for the seedlings but they did. I held back sowing until the end of March beginning of April I think it was because of the "beast from the east" but have to say that I was very pleased with the results achieved. The box sat in my greenhouse and on sunny days I was able to remove the top frame and lamps to let the sun light the box. This setup allowed me to extend the hours of light with the help of a timer.
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