Greenhouse heater

[Amanda1]

My greenhouse is unheated and I usually start sowing around the beginning of April. I usually keep these inside the house until they have germinated and then just use the greenhouse to grow on and to sow when the weather has warmed up. However, having read lots of posts of people who are now starting to see fruit on their plants (I am so way behind!) I think I would like to try growing earlier in a heated greenhouse. However, I can't afford for it to be electric. Can anyone recommend a good greenhouse heater that is also cheap to run? My greenhouse is 8 x 6 ft (and a bit drafty!)

[teakdesk]

There is no cheap heating - if there was we would all be using it to heat our houses !!!!

[rana]

A small paraffin sump heater should be cheap to buy (or cheaper on freecycle). They hold about half a gallon of fuel which lasts for ages if the wick is lit just for cold nights.
They are small enough to be strategically placed (ie. positioned underneath where your seedlings are growing) and provide just enough warmth to keep thing going. Unfortunately paraffin is fairly expensive at around £5 a gallon.

Alternatively place seedings in a waterproof tray on a small electric underblanket set on minimum. The blanket will use very little electric and will deliver warmth exactly where it is needed. I can't vouch 100% for the safety but as long as the blanket is adequately protected and stays perfectly dry it should be OK. I have used this method to great success and it is a hell of a lot cheaper than investing in soil warming cables and much more controllable. If used on a timer for night use only, I estimate the cost of running a blanket at around 30 pence per week.

[Madasafish]

I use a twin burner paraffin one. For nightime heating in a insulated 6*6 greenhouse. My paraffin bill March - early May about £24 (4 off 4.5litres at £5.50/each plus a little more).
Even now night time temps in greenhouse can fall to 3-5C but I don't heat any more and tomatoes/flowers survive...

You can't get much cheaper.. and I start off with the heater under a mini greenhouse on a bench inside the big greenhouse which shows how cold March is. :-(

[Two_Sheds]

My paraffin bill March - early May about £24 (

So if you grow 4 chilli plants, that makes them more than 6 pound each .. not really worth it, in my book.

Just grow one or 2 on your windowsill for the novelty of early fruiting, and the rest as normal in your unheated greenhouse.

[Madasafish]

In my greenhouse I have 15 tomatoes, about 200 bizzie lizzie, 20 dahlias ,40 dwarf and 10 sicilian beans and 12sunflowers. And about 200 begonia semperflorens.. Outside in trays about 500 plants waiting to harden off: all grown on £25 of paraffin.

It gets a bit crowded end April:-)

[rana]

I would think with that many plants in a 6x6 you could dispense with the heating altogether and just get them to huddle together for warmth.

[Alison]

Just grow one or 2 on your windowsill for the novelty of early fruiting, and the rest as normal in your unheated greenhouse.

That's what I do, works a treat and I don't really see the point in normal folks heating their greenhouses, it's expensive, environmentally unfriendly and really not necessary, you don't gain that much time and I find I appreciate the fruit all the more when it comes in it's natural timescales.