Greenhouse heater

[Bal]

Hi can anyone tell me how I work out what size heater to get to heat my greenhouse. I want to use it to keep the temp to 10 degrees. Will this be enough to keep toms and pepper germinated seeds happy as they grow on. I'm planing on germinating them on my old electric blanket. Did it this year and it worked a treat. Problem was I moved all the seedlings to the green house and they just stopped growing. Took for ever to get going again hence all my peppers and chillies started fruiting so late I barely got one crop from them

Ps my green house is about 17 feet by 6 feet

[Alison]

It depends on many things. Do you want to hear all your greenhouse? That would be very expensive and partitioning an area might be better. When will you be sowing your seeds and putting the seedlings in there? Earlier in the year is obviously colder but your plants will also suffer from lack of light levels.

[bearded bloke]

"Bubblewrap" on the inside will help conserve heat, as Alison said partition off an area is probably the way to go, build a framework only a little bit larger than the areayou need

[Jungle Jane]

Its the pot/compost that needs the warmth most,could you do something with heating under the pots to keep the heat right there maybe? But something unelectricutional because of watering? Polystyrene might help keep the pot insulated? Tomatoes were slow to plant out this year because of the cold April/May,I just bring mine in the house a lot like I'm hardening them up for three months.

[Potstubsdustbins]

I could work it out for you but you wouldn't like the result to heat the whole green house. As a rough guide if it's built out of 4mm glass 50'F/10'C at least 10 kilowatts for one degree of frost outside. With the heat loss through the glass I would expect the heater to be running 12 hours a day.

You would be far better looking at the solutions above. A friend of mine as built a large glass cabinet on his greenhouse bench with sand in the bottom, buried a thermostatically controled heater cable in the sand and pops a sheet of glass over this. Works very well for little cost and he can dismantle it for the summer.

[Bal]

Hi thank you all for your help. I am going to bubble wrap it. I only want to heat it once my seeds start germinating in early spring. I have an old electric blanket that I used as under heating for germinating my seeds on this year, which was very successful, but I put them into a cold greenhouse too soon and they all just stopped growing. I wanted to keep them warm enough to stop the shock happening..

[Potstubsdustbins]

Although you have used it with success I honestly don't like the idea of using an electric blanket in such a moist atmosphere.

I have a collapsible wooden bench in my GH, when I used paraffin I placed the heater under the bench itself, this warmed the wood and proved quite successful. I now used a thermostatically controlled electric convector heater that sits behind the bench, on its lowest setting it keeps my 8 x 6 polycarbonate at around 10'c. I just make sure I switch it of before watering and then leave it switched of for a further hour just to make sure. SWMBO has not noticed an increase in the electric bill so it can't use a lot.

[Bal]

Thanks all will let you know how I get on

[unclefudgly]

Just installed my heating solution, it's on the right hand side!