Greenhouse or polytunnel?

We are looking to get a greenhouse or polytunnel but we have a dilemma........We live on a hill a couple miles from the Bristol channel with only open fields between us and the channel. When the wind blows, it blows! Our garden has no trees etc to provide any shelter for a greenhouse OR polytunnel and they would be open to the elements. Being a complete gardening novice I am clueless as to whether either a greenhouse or polytunnel would suit our location best? If so what type is strongest and would be best? IE aluminium, wood, polycarbon? Or are both no-goers because of our location?
Thanks for looking in,
Paul

 

Hi @Paul4321 - I have had both and IMHO it's mostly to do with good foundations and fastening it down. In suburban Stockport I once found that my greenhouse (a hexagonal one) had actually shifted on its concrete base after a very windy period. The only way I could tell was by seeing strain on the tube holding the power cables bolted to the side - no glass cracked at all. I also had a polytunnel in a windy part of east midlands with no problems - I remember the makers showed a video of them coping in a gale - something like this one
My current greenhouse has LOTS of bolts holding it to the concrete!
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I would go polytunnel, I currently grow under glass, and polycarb. The polycarb is more thermal efficeint than glass so you get better frost protection, and better UV protection, but glass can takeca better hammering from the wind when undamaged.
You are only a few miles from me, I would go for a proper polytunnel, not one of these flimsy inch thick tube type, polythene now days, has come on a long way, thinner, stronger, and more protection from UV than polycarb. If you use a commercial polytunnel (Can be picked up quite cheap on ebay etc), and buy commercial polythene, a properly errected tunnel can take the weight of a 14 stone person or winds upto 120 mph. It needs the right supports concreted in, and the polythene attached properly. If you do get a commercial tunnel, and need some help or advice, as long as I am not busy, I can help you, for the princely sum of, plenty of tea, slice of cake, and a bag of chips.

 

I've got no experience of poly tunnels but regarding greenhouses in strong winds, yes it needs to be well anchored down, but the best advice, I think, is dont allow the wind to get inside.
Most are only able to withstand winds from the outside, they tend to explode if the wind gets inside for any reason.

Mine withstood the full force of the 1987 storm when nearly all the others around here were demolished, main reason, the door on mine and the vents remained closed.

 

Hi,

Key question , what size are you talking about ?

Do you have a upper budget in mind as good quality wooden ones can be very expensive ?

Aluminium ones might seem flimsy to some and a few extra diagonal pieces can really add to its strength, but as said, metal or wood, its the base thats key.

Polytunnels generally for bigger areas and perhaps , to some, less pleasing asthetically.

 

@Paul4321 the big question is, what'd do you want to look at and what are you expecting it to do for you?

Every structure shifts and succumbs somewhat in big winds otherwise no one need to worry about cracked caulking or missing roof tiles.

Whatever structure you choose, securing it is a matter of mechanics. Mine are well secured but I still need to square them up now and again. The doorway tells all

Years ago I added two weeny greenhouses that had the twin wall poly carbonate and hated the appearance so bought all clear polycarbonate to replace those. And purely for esthetics.

What do you want to do and what do you want to look at everyday?

Me, I have some sloppy areas but fixed structures must be tidy and pleasant to the eye.

 

Both. Site a smaller grenhouse sheltered from winds by a larger, securely held down tunnel and use plants produced in the warmer g/h to grow on in the tunnel.

 

My findings so far :

8 x 6 Greenhouse with concrete floor - no damp issues, withstands winds in an exposed area, size limits what can be grown. Temperature control can be an issue

18 x 30' polytunnel - damp can be an issue in winter so I keep the air moving with a fan. Cost per metre is less than a greenhouse. No issues with storms in an exposed area. Plenty of space. Double doors each end allow airflow in summer. Polythene will eventually need replacing.

If I could afford it I would have a greenhouse slightly bigger than the tunnel but I cant and I'm getting great results from the tunnel

 

What do you want it to do? Few people ask themselves that first. Germination and providing seedlings can be done in cold frames, window sills etc. so, if the intention is to raise food bearing plants, the structure needs to be of a lean to design sited in an east-west position and, of course, facing south so that smaller crops (lettuces etc.) are grown in the lower, south, part gradually increasing in height and culminating in a wire supported grape vine just under the roof. Any bales of peat, bags of compost, flower pots, watering cans etc. should be elsewhere leaving maximum area for crops.

 

I had the same dilemma for my windy allotment plot.

All I can say is this - the recent strong winds we've had - the allotment poly tunnels fared better than the greenhouses - I suppose because poly tunnels will flex with the wind to some extent. One aluminium greenhouse - smashed glass everywhere - twisted frame - it had been pulled from the bolts that fixed it into a concrete base. So I'd plump for a poly tunnel.

But I've been told that sealing up gaps and not letting the wind in is the key - as has already been mentioned.

 

Here in W Cork, with nothing between us and Argentina, wind's one very real problem but suitable anchoring of a greenhouse should keep it intact. Having said that, I haven't built the one I've designed (too many birthdays) but, for general use with a selection of crops of varying heights, a tunnel's high point down the east/west centre will almost certainly leave plants on the north side in the shadow of those in the middle, and thus deprived of sunlight?

If you go to any of the old stately homes, e.g. Hampton Court, the greenhouses are invariably constructed as lean to's against a south facing wall for this very reason. All the impedimenta was kept in the building behind, i.e. not in need of additional warmth or sunlight.

 

Thanks all for the very informative responses, and the offers of help. Very kind indeed and much appreciated.
Having read the responses and looking at the options suggested, I was thinking of a greenhouse size 12ftx8ft which I was planning on anchoring to railway sleepers (the real ones, not the diy shop ones) sunk into the ground. Do not really want to use concrete for environmental reasons unless I really have to. I do realise the old sleepers have been treated with chemicals that can be harmful in the ground but the recycle for me cancels out the negative of sleepers compared to freshly made/laid concrete. Thats just a personal preference and I am open to other suggestions.
As I am still at the gardening novice stage, I had planned on growing the usual tomatoes, cucumbers, peppers etc with a view to getting more experimental as time goes by and I gain more knowledge and experience. Hence the larger size greenhouse to start with rather than starting smaller and having to upgrade at a later date.
If anyone can recommend a good, sturdy aluminium 12 x 8 greenhouse I would appreciate it or are they all much the same?
Thanks again everyone,
Paul

 

Beware of using sleepers around ground that you are going to plant in. As you say, they are loaded with chemical which will leach into the soil.

12 x 8 is a decent size but it will be filled in no time.

Good luck with the project

 

There are lots of choices. My personal favourite and what I have bought are the Palram ones as they do flex in high winds and the polycarbonate does not crack, yellow or pop out. The clear ones are very nice looking too. They do block uv rays so it is safe to tan in there too! The doors swing which is an added bonus because you will never have to worry about sticky channels/tracks. After a windstorm, you can loosen some of the nuts inside and square it back up. Usually about a 1/2" at most is what I have found. And that only once or so a year.

 

Do you reckon they do them in the size I need