Cost of heating a greenhouse overwinter

My little 6 feet square polycarbonate glazed greenhouse is finally ready. The bubble wrap is fixed all round the inside, and most of the plants are in.
I'm heating it with a 2KW fan heater on frost guard setting, and have a max/min thermometer to see how it copes. And ,out of curiosity, am recording the power used by the heater for the duration of the winter. Several people have wondered what it costs, so now there will be some sort of answer. I'll post some interim results later on.
Here are the inhabitants


Nik

 

I have no such interesting occupants of my 6-8' glass greenhouse. It is crammed full with shrubs in containers, small olive tree, fuschias, geraniums, and hordes of cuttings. I am running out of room and this is my first year....I also have an electric heater which I will set on frost guard, and a thermometer, but I haven't put bubble wrap round- we'll have to compare later. Here in Wiltshire there was one just below zero frost [August!!] but so far in the garden still above zero. I keep hearing threats of a very cold winter to show us that we shouldn't become complacent about our tender plants.

 

Liz
I've heard this threat of an abnormally cold winter too. I've even taken the hosepipes in, and will lag the taps as well.
Must buy some mealworms for the Robin.

 

Total power consumption so far has been 0.55KWh, due to the extractor fan. Everything is still growing in there, obviously we were a bit hasty.

Sadly the thing leaked like a sieve, and the sealing round the bottom is very efficient, so it has been flooded with 2" of water a couple of times. A polythene fly sheet has stopped it though.

One intersting thing, lemon flowers in Aug 04 set fruit which are now nice and fat and turning yellow ready for Christmas G&T's. I've not had that happen before.

Nik

 

Decided today that I'd better start heating the greenhouse. Temp. outside last night was just above zero, but still about 2degs inside the greenhouse. I finally took pity on my 2 biggest fuschias and put them inside the greenhouse. They're still trying to flower but wind and rain have spoilt most of the flowers.
Foolish question for today- does bubble wrap insulation go inside or out of the greenhouse?

 

Inside, you can get little plastic clips which lock into the channel in the aluminium frame (if that is the sort you have)

 

Yes, it is. I will try tomorrow, thanks!

 

They are called 'alliplugs'

 

I haven't yet started to heat the greenhouse, without any bubble wrap the temperature inside the greenhouse at night is still 2-3 degrees C. I keep listening for frost warnings! Some of my geranium cutting are trying to flower already and fuschias are producing new flowers.... :confused:

 

To maintain a minimum of 5.7C in the greenhouse last night took 9.5Kwh. Projecting this throughout the winter means that the lemons are going to cost about �£10 each. I'd better get some very nice gin to put them in. :D
Nik

 

That seems a lot Nik, for a 6ft square greenhouse.
I think I'd run it at a lower temperature, maybe 3 deg minimum.
Just out of interest , what was your outside temp.

 

cold enough to make plenty of ice?

Where's the tonic ?

 

Pete
9.5Kwh seemed a lot to me, and 5.7C was a little higher than planned, but I'm still getting to grips with the thermostat setting on the heater. I agree that 3 or 4 degrees would be more reasonable. The outside temp went down to -2C on the night in question.
And to cap it all one of the lemons has got a little hole in the side. I'm not sure whether something has eaten its way in or out.

Tortuosa
The tonic is safely in the fridge, along with a bottle of Gordons Export, just waiting for a lemon. :D

 

Nik

Where did you get your consumption meter. I know they exist but have never seen them in the shops, or even on the internet in this country. They are useful to have for a variety of reasons.