The Accidental Smallholder Forum

Growing => Vegetables => Topic started by: hafod on November 19, 2013, 09:47:14 am

Title: Keeping a polytunnel warm (well frost free!)
Post by: hafod on November 19, 2013, 09:47:14 am
Hi,
We had our first frost and a sprinkling of snow last night. We have already insulated the poly tunnel with bubble wrap, cover all the plants in fleece and have a small heater to help keep things from freezing but I was wondering if anyone had any other hints and tips to help us through the winter. We had put in barrels of horse manure thinking that they may radiate heat as they decomposed but I don't think this is working. We only have a couple of cm's of soil under the polytunnel so digging down to create a heat sink isn't an option.
All ideas appreciated. Thanks
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: Mrs South on November 22, 2013, 02:19:57 pm
We have just bought a small paraffin heater so it's not on yet but I'll ask hubs to sort it in the next week or so and let you know how we get on.

Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: pgkevet on November 23, 2013, 07:18:53 am
I tried a couple of those parasene greenhouse heaters and despite pfaffing about some hours trimming/setting wicks and even buying 'real' paraffin instead of using red: when i finally shoved it into my citrus house overnight I ended up with a horrendous soot-fest that took a long time with a backpack sprayer to wash off the house and leaves.

I went electric with it just at frost-free or the running costs are crippling
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: JulieWall on November 23, 2013, 08:39:26 am
Hubby painted some breeze blocks black to stand his seed trays on one year. They act like little storage heaters storing up heat in the day and releasing just enough residual heat at night to keep his tender seedlings from chilling down.
Something else he uses are hurricane lamps. He made a hanging seed bench after the mice ate all his seedlings one spring, so he hangs the lamps underneath it. http://theroundhouse.freeforums.org/post13344.html?hilit=hurricane (http://theroundhouse.freeforums.org/post13344.html?hilit=hurricane) lamps#p13344 It helped the germination rate enormously. He has also used alkathene pipe to erect temporary hoops over his beds to cover with plastic for tender plants, a hurricane lamp will keep a small area like that very warm.
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: Victorian Farmer on November 23, 2013, 10:52:37 am
This is a pallet burner for a frends lambing shed .Some think like this will burn eney think for heat a big log 7 houres .So a smaller burner will work like mine .
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: cloddopper on November 24, 2013, 09:47:28 pm
I use candle power to keep my glasshouse fairly frost free but use a thermostatically heated bed covered in fleece to keep really tender things alive .

I make my own candles for gardening,, found that last year I needed bigger longer lasting candles .
This June I purchased on eBay @ £12.50 in total  a 10 inch by 3 inch dia aluminium candle mould and 20 mtrs of suitable wick.
 
Over the years I've picked up  various things for melting scrap candle wax ( got 30 kg of old bits of candles a couple of months ago from Freecycler ) a leg wax heater  and various things that helped make my candles .
The leg wax melter is brilliant as it does not overheat the wax , the tin of leg wax that came with the melter was poured into the compost heap & is my now my wax melting pot ..
 I've cast five another ten inch candles this last week .. got one on in the glasshouse tonight as it's a minus 4oC forecast.
 Each candle set in a stainless steel bowl  lasts just over 72 hrs. of continuous burning. 
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: kimicals123 on December 08, 2013, 08:08:08 pm
Hi

If you use candles to heat the space up, place inverted terracota pots over the top of them to store the radiant heat from the candle flame.
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: JulieWall on December 08, 2013, 10:51:39 pm
I always wondered if the fumes from our lamps or from paraffin heaters were bad for the plants, anyone know?
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: bloomer on December 08, 2013, 11:39:32 pm
Doubt it as they mainly emit co2 and water, both of which plants love...
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: clydesdaleclopper on December 09, 2013, 05:46:55 pm
IBC tank full of water and painted black. It will act as a heat store.
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: regen on December 24, 2013, 08:58:36 am
"Doubt it as they mainly emit co2 and water, both of which plants love..."

And loads of hydrocarbons- check out the cobwebs after a nights candle burning!

Google "the Garden Impressionists"  On their blog is the description of a system based on compost which has been used to keep a greenhouse frost free for a year in West Wales.

Regen
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: ScribbleUk on December 24, 2013, 03:46:49 pm
This might be worth a read.  Probably a lot of effort but saves on electricity, gas, or paraffin. 

http://midwestpermaculture.com/2012/03/building-a-jean-pain-style-compost-pile/ (http://midwestpermaculture.com/2012/03/building-a-jean-pain-style-compost-pile/)
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: JulieWall on December 31, 2013, 12:06:38 pm
Our outdoor Hugel style beds are constantly warm because they are full of composting matter and produce humungous veg and roots. Perhaps the same principle could be adapted to heat the beds in a polytunnel like under floor heating.
Title: Re: Keeping a polytunnel warm (well frost free!)
Post by: Womble on December 31, 2013, 02:27:52 pm
We have a very old Eltex propane heater in our greenhouse. 

(http://i.ebayimg.com/t/A-NEW-UNUSED-ELTEX-PROPANE-GAS-GREENHOUSE-HEATER-/00/s/MTM0OVgxMDc5/z/md4AAOxynRRSRBeA/$T2eC16F,!zkFJDJpEl6eBSRBe!F8Gg~~60_12.JPG)


It's thermostatically controlled, and uses 1/3 to 1/2 a red 47kg propane cylinder per season (i.e. £20 to £30 worth). Because the summer is short in Scotland  :roflanim: , we use it to get everything started early in the greenhouse, which gives the plants a head start once they're planted out into the polytunnel.


No electricity needed, no wicks to trim (once it's set up, it can just be left), and no soot issues. Highly recommended  :thumbsup: .

I did see plans once for a combined hen house and greenhouse. It was basically a potting shed, with the back half used as a hen house, the idea being that the heat from the hens kept everything from freezing at night.

I think you'd need lots of chooks to make that work though, since I often find the drinker inside our hen house has ice on it in the mornings (the hens are fine of course).