Polytunnels.... some questions

[GreyCat]

OK, now I'm at the new place, I want to sort out a polytunnel.

Back when I had an allotment at the old place, I had a small (2m by 4m) tunnel, brilliant thing...... not big enough...... and eventually I managed to make it strong enough not to blow away in winter. I say eventually because I bought cheap, and following the advice of the old hands, it needed a lot of extra wind bracing (I used pallets to build side walls) and I replaced the cheapo cover (lasted 2 summers only before ripping) with proper horticultural plastic.

So, at th enew place I have a decent flat space where I can put for a tunnel of up to 9 metres/30 foot by 4.5 metres/14 foot and have a good space around it for maintenance/build. (The whole of the ~1 acre plot is designated "garden" by the planning authorities and it's well back from the road and house). Also I have a couple of kiwis and a grapevine which really need to live in a polytunnel all year around, and my small Morello cherries do much better under cover- they are currently in a large trough hogging my little greenhouse- and my quince trees also prefer shelter, so they may need to go in there. so even before considering veg planting, I have a bunch of things to live in the tunnel all year around- hence the proposed size. The permanent stuff can live in a bed down the centre, with the side beds for seasonal growing- veg and also some herbs that don't really like the wet climate.

So. My thoughts are to buy a good quality tunnel from somewhere like Northern Polytunnels, First Tunnels or Highland Polytunnels- wondered if anyone had any experience of them, and how they compare to cheapo tunnels for strength? With the price difference, I would expect a much stronger structure- is that the case?

It's SW Wales so it's wet and windy for much of the year. Theres a big wind farm on the top of the hill, although thankfully we are in a dip, so relatively sheltered compared to the folks further up the road... but still a windy location.

Then there's the installation. I can do it myself, with some minimal assiatance on a good day from the other half.... or the retailers of the tunnels I mention offer an option of having someone come and build it. I know from the challenges of my previous allotment tunnel that it's a chore, and it's not easy to do the essential part of getting the plastic tight enough. Much as I like to DIY and do a lot, sometimes I need to be realistic- and in truth I'd rather be growing than building (nor am I getting any younger...). A good build in the warmer weather should help optimum tunnel life.....

If the costly tunnels are not worth it, the other option is buying a couple of el cheapo 3m by 6m tunnels and putting them at right angles, then (1) reengineering them to be strong and (2) getting proper horticultural plastic to cover them. At the end of that, I wouldn't save much money and it's a lot of work in the (inevitable) rain, so I'd rather just get a decent strong tunnel in the first place.

I'd be interested in thoughts of folk on here- any experience of particular types/sizes of tunnel? DIY build vs have it built ofr a tunnel of the size I am considering?

Thanks in advance....

GC

 

[Pattree]

Have you talked to local horticulturalists who have tunnels?

Without question I would have it built by the supplier. That way you should get some warranty.
I helped build one at Pershore College long ago and watched my mate lifted off the ground in a light breeze.

All the reports say that UV is your worst enemy but in my limited experience a badly fitting cover that can rub against the frame shortens it’s life quicker.

Very best of luck with your venture.

 

[Laurentius]

Funny I just read this as I am looking for the same thing too, I am downsizing my allotment plot and losing a polytunnel in the process. A good idea to keep it from blowing about too much is to put garden netting over it and peg that firmly into the ground.

 

[Toddy]

Twenty + years ago I bought a Rion polycarbonate 8 x 6 greenhouse....cost me all of £200.
It's still sound.

I don't know what it'd cost now, but honestly, I'd think about it.
It's not glass, it's been through horrendous gales, three foot of snow, torrential rain, baking sunshine, and it's still sound.
It doesn't owe me a ha'penny.

I laid down old slabs and the base is bolted onto those. It hasn't moved in all those years.

 

[Laurentius]

Twenty + years ago I bought a Rion polycarbonate 8 x 6 greenhouse....cost me all of £200.
It's still sound.

I don't know what it'd cost now, but honestly, I'd think about it.
It's not glass, it's been through horrendous gales, three foot of snow, torrential rain, baking sunshine, and it's still sound.
It doesn't owe me a ha'penny.

I laid down old slabs and the base is bolted onto those. It hasn't moved in all those years.

I had a neighbours polytunnel lift off and land on my allotment having flown all the way over a tall hedge. That neighbour never had any luck with any structure on his plot, he had a greenhouse before that and all the glass broke and a bolt together aluminium shed which fell apart whereas my erzatz shed built out of spare bits of corrugated iron and old doors has withstood storm and tempest over these past 12 years since I built it.

 

[richy3333]

Northern polytunnels are good. If it's windy buy fatter steelwork and have smaller spacings on the hoops. Fitting the sheet is not a one man job, particularly if it's windy! Expect the plastic sheet to last around 7 years although ours managed 9 years and was still going strong when we moved. Reserve an area for sitting. They get really warm inside and its great chilling in one whilst its raining outside.

 

[Astrochicken]

100% agree on getting the manufacturer to install - I've seen two polytunnels turn into giant-sized plastic-wrapped kerplunk games by the wind, with one of them having been declared by the maker to be Scottish Highland / Island rated, and in both cases the buyer decided to do the install themselves. It may seem expensive to pay for the installation, but it could easily be worth it if something goes wrong, even if it's just the skin getting torn / nicked during the install.

Trying to get rid of the mess of the most recent one has meant the owner having to wait until someone can come and get the metal poles out and cut up to take them away too, so they've had no tunnel all of this year meaning a loss of the growing season.

 

[Laurentius]

Fitting the sheet is not a one man job, particularly if it's windy!

You need a polytunnel raising, like the barn raising in Witness. Generally on our allotment people gather round to help each other putting them up.

 

[GreyCat]

Northern polytunnels are good. If it's windy buy fatter steelwork and have smaller spacings on the hoops. Fitting the sheet is not a one man job, particularly if it's windy! Expect the plastic sheet to last around 7 years although ours managed 9 years and was still going strong when we moved. Reserve an area for sitting. They get really warm inside and its great chilling in one whilst its raining outside.

That's really good to know as I was looking at their stuff. I was looking at the ones with fatter tubes (the 35mm tubes).

I have come to the conclusion that paying for installation and concreting in the ground anchors is the way to go. Yes, it's costly, but so is the time and heartache of re-doing everything. For a smaller tunnel I'd probably to it myself, but i am looking at a 9 metre by 4.5 metre tunnel.....

Not sure yet whether I'd need to prep the ground anchors in advance, I will call the chosen retailers and ask for more info. The area of ground is a mix of stone and earth, so I suspect the ground anchors (at least for the 4 corners) will need concreting in at least a day before the tunnel goes up. That's not a biggie, I can happily do that.

GC

 

[GreyCat]

I had a neighbours polytunnel lift off and land on my allotment having flown all the way over a tall hedge. That neighbour never had any luck with any structure on his plot, he had a greenhouse before that and all the glass broke and a bolt together aluminium shed which fell apart whereas my erzatz shed built out of spare bits of corrugated iron and old doors has withstood storm and tempest over these past 12 years since I built it.

Yeah, I had a shed like that on my allotment. I inherited it in a poor state, fixed it up with scraps and painted it with left-over Cuprinol Colours (a fetching sea green!). The other allotmenteers reckoned it wouldn't last 12 months, but it survived 5 years of storms- and I passed it onto the next person.... I never locked the door, just bolted it shut, didn't keep anything of value in it, so when thieves visited the allotment, mine was the only undamaged door- they opened it easily, saw nothing of value, and moved on....

GC