How should I heat my greenhouse over winter?
Doreen Smith, by email
Stefan says: You’re facing the problem many gardeners have: heating a greenhouse can be expensive. The capital outlay alone can make an efficient electric heating system prohibitive, mainly because of the cost of installing a safe electricity supply, which will require a buried armoured cable, fitted by a qualified electrician.
I’ve seen far too many lengths of cable coming from house windows and plugged into a domestic socket, then draped over makeshift supports to take power to a greenhouse. They’re horribly unsafe and gardeners shouldn’t be tempted to try supplying electricity to their greenhouse in this way.
Understandably, therefore, a paraffin heater is an appealing alternative. Small paraffin heaters are available at under £30, but it’s important to realise they’ll do little more than keep out the frost. They’re claimed to run for around 60 hours on a 4 litre tank of paraffin, which costs around £2 and so works out at around £6 per week. So if a paraffin heater is the only option, and you’re paying for the fuel, I’d advise choosing a larger model if at all possible, so the temperature will be elevated a little above just frost-free. But it will never be more than that.
Although they are appreciably more costly, starting at around £140, anyone wanting to do more serious greenhouse gardening should think carefully about