green house temp

[onion man]

i have 2 large propagators but i'm running out of room inside so i will have to put them outside so here is the question what is the best temp to keep the greenhouse over night to ensure my seedlings so not die off is paraffin a good idea as my old man says its no good in greenhouses

[Kristen]

Minimum of 10C for things that are tender (Tomatoes, Peppers, Melons, Cucumbers [don't sow then yet though!], etc.)

Onions, Brassicas, Leeks etc won't need any heat at all (but may appreciate some shelter)

I don't like paraffin much as it generates a lot of condensation and is the heaters are usually only On or Off! Gas creates less condensation and may have a thermostatic control

Please can you add your location? There should be a Pencil Icon on your profile here

[Two_Sheds]

My unheated gh (temp is above freezing but not much above) is stuffed with seedlings at various stages - all hardy stuff though, the toms and chillies are indoors on windowsills

[Alison]

My unheated gh (temp is above freezing but not much above) is stuffed with seedlings at various stages - all hardy stuff though, the toms and chillies are indoors on windowsills

Like she says

[Norm]

I have toms, peppers and this years show leeks in a paraffin heated greenhouse. External min temp -6, min internal temp +2.5. The whole thing is lagged with bubble wrap. Been doing that for 12 years with no problem.

[richardbees]

I've always used paraffin for heating with same temps as Norm (above) and never lost any seedlings - but it is a good idea not to over water. Ideally I'd use an elec heater on thermostat but my GH is nowhere near a supply. Calor Gas heaters are prohibitively expensive.

You're much more at risk from a tray of seedlings baking behind the glass from Spring sun so don't forget to use some shading by the end ofg this month!

[Kristen]

Calor Gas heaters are prohibitively expensive.

I wonder if there is a comparison of running costs?

I reckon the Parasene paraffin heaters are about £20 - 40, and the entry level Calor gas heaters are £60 - £80. (I was lucky and got one, with a gas bottle, of eBay for about £30)

The gas heaters will be 1.5 - 2.0 kW - which I would think would be more than the small Parasene ones? and being thermostatically controllers the gas would use less fuel on a "warm" night (assuming you set your Paraffin heater at a risk-free heat output )

I am also thinking that Paraffin heaters are likely to be more expensive to run, for a given amount of heat output, than gas?

So perhaps the difference in running cost could repay the extra capital cost in a season? I'm guessing though ...

If you had to buy a gas bottle, and regulator, that would be much more expensive, so comparison probably only works if you already have a gas bottle for a summer BBQ or somesuch.

[richardbees]

kristen, which calor gas heater have you got as I haven't come across thermostat controlled ones? Mine is a 'superser' and looks like an old three bar gas fire but it's either on or off.. ..I only use it to warm me when I'm down there!!


A 15kg gas bottle which lasts 120 hrs on the 'one bar' minimum setting and the bottle refill /now costs £33.

My Parasene two burner (4 wicks) paraffin heater lasts about 72 hrs on 1 gal /now costs £5.50 I don't know what the heat output is but it's enough to keep min 2C in hard frosts.

I'd prefer not to use paraffin as, apart from the condensation, there is a build up of soot all over the inside of the roof.

Richard

[Potstubsdustbins]

Kristen,

I think you are correct in your assumption that once purchased the running cost of gas would be less, I assume you have the heater made specifically for GHs.

I use paraffin for ease and to try and save a little space. I use a Parasene two chimney 4 wick heater but rarely need to light both burners.

As to soot, when burning any fossil fuel soot means carbon monoxide, care should be taken to adjust the flame correctly and with paraffin heaters this can only be done after the heater as been lit for 20-30 minutes. This allows for the slight rise in the temperature of the fuel and gives more efficient burning.

Colin

[Kristen]

kristen, which calor gas heater have you got as I haven't come across thermostat controlled ones? Mine is a 'superser' and looks like an old three bar gas fire but it's either on or off.. ..I only use it to warm me when I'm down there!!

A 15kg gas bottle which lasts 120 hrs on the 'one bar' minimum setting and the bottle refill /now costs £33.

I know the type you mean, but its not like those "1 / 2 / 3 bar fires", but is purpose designed for greenhouses. Here's one - costs £80 though, and I'm pretty sure I've seen them nearer to £60. Might be worth looking for "Eden gas heater" on ebay as that is the name of mine - it looks the same as the ones now called "lifestyle", so maybe the name changed along the way.

Lifestyle Gas Greenhouse Heater 1.9kW

My Parasene two burner (4 wicks) paraffin heater lasts about 72 hrs on 1 gal /now costs £5.50 I don't know what the heat output is but it's enough to keep min 2C in hard frosts.

I'd prefer not to use paraffin as, apart from the condensation, there is a build up of soot all over the inside of the roof.

Useful figures, thanks. I've never dedicated a gas bottle to mine to know how long it lasts, and I haven;t been able to find any "running costs" on the internet either

[Kristen]

Here's one on eBay for £60 inc. regulator - if you live near Hertford

TCM Eden propane gas greenhouse heater on eBay (end time 08-Mar-11 18:46:15 GMT)

[richardbees]

Thanks! I had absolutely no idea there were 'domestic' size thermostat controlled gas heaters.......though come to think of it, it was quite some time since I looked into it!

The key question is what is their consumption (e.g. hours per kg) on their lowest setting and what is the lowest setting? I light my Parasene, if frost looks likely, when I leave in the evening and it stays lit until I return the following pm. Perhaps you'll have the answer to this by next winter, Kristen, it gives me a year to source a real cheapie! I'm SouthLlondon and any more hard frosts are unlikely.

I enjoyed your garden blog - that's a lot of veg!

[Chef_uk]

I still have a couple of broken panes in mine :/ But everything seems to ticking over nicely in there and some warmth can be found. Hardening them off for a week first seems to have done wonders for them. Also I may be wrong but the stems of the broadbeans have got thicker and this may be from the odd breeze that comes in via the broken pane. crazy theory but a subtle breeze can be felt.