Polytunnels - maintenance and running.

[Gardengatecottage]

Hi all.
The frosts have arrived and everything is slowing down in the tunnel.
We always have fresh salad on Christmas Day for breakfast (with sliced smoked venison and a small sloe gin) ... real local, high quality, low priced produce. Yes, I know venison is dear (sorry) but pound for pound, higher quality, less is more, enjoyment over over eating.
I digress ... the upshot is, we need to keep the polytunnel warm now the frosts are with us and desire, nay, need salad etc. We do not have a quiet period in the tunnel ...
We usually put hay bales into the spare areas of the tunnel (back door, side paths etc.) which absorb the heat of the day, store it and let is out through the night. It seems to work, we don't get vermin nesting, there's somewhere to sit and there's always that musty smell ;o).
Being plastic, the tunnel cannot have a stove... we didn't put in an electricity supply so tube heaters are not an option (plus we wanted to be as eco as possible).
If you guys have any extras or better ideas, it would be good to hear them. Have fun in your gardens ... keep warm !

[diggernotdreamer]

ok, as no-one else has answered, I will tell you what I have done in the past.

Sectioned off the part I want to keep warm with bubble wrap as curtains, although that was in a greenhouse and they do keep warmer than polytunnels, but it could be done.

I use heavy duty fleece in certain places that I want to keep warm, stick in hoops and drape the fleece over the crop, I use bubble wrap as well in conjunction and take it off during the day .

When I scoop the embers out of the fire, put them in a metal bucket and put them into the tunnel, sit the bucket on a paver or flat stone and put a bit of tile or something on top of the bucket, works quite well

Bring in a huge water butt and fill it, the water will absorb heat during the day and expel it at night.

Heat bricks or stone on the stove and put them in the area

Put in a chicken tractor to clean the beds over winter and the heat of the chickens warms the place

[Green Aura]

We've got a heat sink in our polytunnel, which is warmed by a solar-powered fan. I've written about it loads of times so I won't bore everyone with it again, but if you do a search in the box (top right on the banner) it should come up.

[Gardengatecottage]

I like the idea of the fire ashes ... I'd forgotten about them. I used to take a bucketful out to my old Ford Anglia when I was a lot younger, it had no carpets and would be toasty by the time I had to go to work. When the cold seriously kicks in, I think we'll do that. We do use fleece for the unhardened crops and use it outside on the raised beds - we purchased 3 rolls from eBay a few years ago and it has proved invaluable. The chickens sound a good idea too! A bit reluctant to let them loose as they got in about a week ago and 90% destroyed the salads :o(
I'd love to have put in a heatsink/panel ... I think in hindsight it was an error - at least not to have put pipes in for a later installation. We concentrated more on ease of work, maintenance and safety of the tunnel for when the farmer next door 'takes the cut' (mows the meadow for us). We put in 10 raised beds for ease of planting, rotation, control and fleece covering.
The farmer was petrified when he saw the tunnel. He wouldn't mow for the first season in case he split the plastic somehow. He gets around 8 big round bales a year from the meadow (we don't charge him) which he feeds to his cows over winter. In return, he gives the manure which is perfect for the beds. We have been very lucky really, we have had salads and new potatoes every winter so far.

[Gardengatecottage]

Huzzah !
We have cleaned the polythene of the tunnel ! It gets done every November to let more light in over the winter period. There's never much gunge as such and takes little effort to remove but the difference once done is SO good. True to form, just like when you wash your car, it rained afterwards to give a good rinse (or is it only me who gets this treatment?).
We used a very old, soft real bristle house broom taped to a long pole. Only a mild detergent is needed where we are (we have extremely clean air) so we used a little Ecover ecological dish-washing liquid in warm water, then a gentle hosing with cold water.
The polythene was nice and tight due to the cold and made the whole job much easier.

[marshlander]

Bob Flowerdew has a smaller tunel inside the big one for melons & bananas.

Here's one old thread, there are probably more viewtopic.php?f=55&t=22026

[Gardengatecottage]

That sounds like a good idea ... probably gets stifling in there ! A great place to sit with a nice white wine ...

[diggernotdreamer]

I built a hotbed in mine about 4 days ago, the thermometer sat on top was reading 20 c this morning, will be coaxing a few more salads and cut and come again stuff on the hotbed now.

[Gardengatecottage]

How did you do the hotbed ? is this a compost pit idea ? we tried a compost bed once and it seemed to work although there was little evidence of extra warmth ... saying that, we were very new to tunnels and perhaps in our enthusiasm, we overlooked (or overcooked) something.

[diggernotdreamer]

My hotbed is sort of based on the Victorian Hotbed, except I don't dig a hole, if I dug a hole I would just hit rock so I don't bother digging holes anymore.

I bedded my ducks on straw, turned it over a few times so the cleaner bits got pooed on. Barrowed it into the tunnel to one of the beds and put in a layer and watered it well, put another layer and watered that and so on until it was all used up, I made it with a flat top. Left it for a couple of days and checked in the middle for heat. It got hot very quickly so I just made small declines in the top and stood my pots in and a tray of modules with a clear lid, the things that are in there have grown in just a few days, larger than other stuff still on the bench which was all started off at the same time. The heat should stay in it for a while, when it goes cool, I will rebuild into the bed next to it, add a bit more chicken, duck or alpaca poo and water again for a reheat. In the meantime, will bed the ducks on straw again so as I have more material to build another one. When I checked this afternoon, the thermometer was reading 15, which is pretty good. Covered with fleece last night and none were frosted this morning

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[Teadrinking]

I'm liking this a lot. Do you think you could get that kind of temp with cow poo and straw? I know chicken poo creates some serious heat but no chickens on our site at the moment.

[diggernotdreamer]

Reckon any poo would do, the farmers here pile it in the fields in winter and you can see it steaming away, needs to be fresh though.

[Teadrinking]

Any poooooo will dooooo. Grand. The police horses get exercised up and down a path by our lotty so we'll go out and get scooping. Should be a lovely job.

[doofaloofa]

I have a qustion on construction

if I get a short length of wide plastic and run it with the folds running widthways is this OK?

I will save €50 getting a short wide piece rather than a narrow long piece