Polytunnel v Greenhouse

Hi all - three years ago I bought an 8ft X 6ft greenhouse (you know whats coming next) and within two weeks after assembly I realised it was to small far to small.

Now I have decided it's about time this wee glasshouse went and be repalced with someting of a more sensible size.

So the garden has been redesigned to accomodate a structure of about 25ft X 15ft or there abouts.

But talking to friends who have polytunnels and after viewing them I must admit that I think a polytunnel may be a better option than a greenhouse.

And the better options are not just based on the low price compared to greenhouses.

Have any of you had first hand experiance of polytunnels?

Are they as good as my friends, and manufacturers, make out?
Leucojum

 

Hi Leucojum had the same problem myself run out of room in the g/house so errected a 20x10 p/tunnel as well (still not enough room)the problem with p/tunnels is stabilizing the temperature it's much easier in a g/house with auto vents and being able to insulate in winter with bubble wrap something that is difficult to do in a p/tunnel,If you are contemplating heating a tunnel that size you are in for some big bills,what I have done in my p/tunnel is built a small tunnel inside for tender stuff I heat this and any heat that escapes heats the inside of the main tunnel helps keep the frost out.If you decide on a p/tunnel get as much ventilation as possible in summer it's a devil to keep them cool.

 

I had similar thoughts Walnut about heating a small section. As for ventilation, I can see this as a major problem as temperatures rise. Double doors both ends is a must. I was thinking of having base rails instead or burying the poly in the ground. Is yours buried or do you have base rails? Base rails look much less work and might be able to modified somehow for added ventilation. What sort of temperatures can you maintain in your heated section through the winter?
Leucojum

 

If I had the choice I would go for both, the greenhouse for starting things off and the polytunnel for growing them on.

 

Yup daitheplant, given the choice so would I. But as we are having a new garage and extension to our conservatory space is limited. Although our garden is quite big we want as many beds and borders as possible. Why are gardens never big enough???
Leucojum

 

The same reason why greenhouses are never big enough.

 

We've got a GH and a small tunnel Leucojum. I put up the tunnel two years ago and it's been great - I can garden in the rain!
I buried the poly but it was a horribly heavy and mucky job (February) and if I were to do it again or when I need to replace the poly I'll go for base rails.
Something else to think about before you start construction is putting in an irrigation system.

 

That's a thought Dave W, irrigation! I presume the polytunnel manufacures provide a system? Need to get hold of some brouchers.
Leucojum

 

You can get overhead systems from the suppliers but we use a ziz-zag perforated hose that only cost a few �£ from Lidl and works fine. We've also got a timer that we can attach if required - again only a few �£ from Lidl.

Not the only suppliers but here where we bought our tunnel -
http://www.firsttunnels.co.uk/

 

leucojum go for the base rails better than burying the polythene,also go for side ventillation the full length I only did one side but will convert the other side this coming year you can add top ventillation too,the small structure insidehas abench with a 2ft tube heater underneath and maintains 6c when the tunnel dropped to -2c the other night.As Dave points out firsttunnels is worth a look.

under construction


the whole of the r/h side winds up and down for vetillation.



click to enlarge

 

Are these poly tunnels difficult to put up because we are thinking of getting one for our new village allotments when they are up and running hopefully by the spring?

Also I read in a gardening magazine,Grow Your Own I think it was that it costs as much to replace the polythene cover after a couple of years as what it does to buy the tunnel in the first place which would work out quiet expensive in the long run.Any advice on this would be most helpful..Thanks

 

Have a look at the link I posted above Kandy. There is VERY comprehensive info on that site. Tunnels are not difficult to put up, it takes a bit of time and you have to measure the base carefully to get it square and the hoops in the right places. Covers are reckoned to last a minimum of 4 years and in some cases up to 10 years. Re-covering shuld be in the region of 15% to 20% of the total original cost.

 

Hi Dave,Thankyou for the link.I had a quick look at it this morning.There is also an advert for them in the gardening mag I reffered to above and I have also seen an article all about polytunnels in an earlier addition so will have to re read it and show the link to Mr Kandy.Thankyou for your advice

 

Thanks for all your advice. I notice walnut you have slabbed the whole ground, I was thinking of covering the whole ground with a weed barrier, slabs down the centre full length and shingle both sides of the slabs. The idea is to have benches both sides. Has anybody used weed barrier and shingle before, is it any good? That's a brilliant idea for ventilation walnut, does it seal ok in the winter? Like the idea of the Lidl irrigation system Dave W, I think I'll go for that. Looked at firsttunnels the choices are endless, spent a fortune just looking!
Leucojum

 

Leucojum it is only slabbed for the fist 5ft and down the middle the rest is 6" of white stone chippings on a heavy duty membrane, sprinkler system down the r/h side, the vent system when closed isn't a perfect seal but when I fitted the cover I left a 6" overhang on the outside which helps to prevent draughts in winter, it is set on a course of building blocks.