Polytunnel

Gardening to 'grow your own food' from square foot to half an acre !!
Post Reply
User avatar
KathJ
Longlasting Laner
Posts: 934
Joined: 12 Sep 2012, 13:13
Gender: Female
Location: Shropshire

Polytunnel

Post by KathJ »

Now we have more space we're thinking of getting a polytunnel. Never having had one before we don't really know what to go for although the size would be 10ft x 20ft. I've just looked online and it seems that you have a basic price and then add on all different extras. From experience can anyone advise what we absolutely must include and what we could do without? Thanks!
Kath xx

Mum to my beautiful girls Lucy, Holly, Rosie, Hettie, Polly, Ruby, Lily, Penny, Gracie, Maisie, Molly, Evie and my gorgeous boy Toby

RIP my beautiful Ranger, Roxy, Bluebelle, Poppy, Speckle, Daisy and Honey xxxx
User avatar
lancashire lass
Legendary Laner
Posts: 6527
Joined: 28 Jun 2007, 15:17

Re: Polytunnel

Post by lancashire lass »

it depends on which polytunnel you are looking at - I got the "cheaper" one which is a steel frame and a green checked cover so the additional essential for me were hot spot tape to protect the cover from chaffing and being damaged from extreme heat (hot metal frame). And of course, the ground pegs (though lots of tent pegs has worked just as well)

Not sure what extra for the more expensive polytunnel. Perhaps you could add a link to the ones you were thinking of getting.
Freeranger
Legendary Laner
Posts: 3171
Joined: 17 Apr 2012, 10:13

Re: Polytunnel

Post by Freeranger »

I was hoping someone who knew what they were talking about would answer this query because I looked at them as well, and ended up more confused than I wanted to be. Options I saw were:

Clear or green net type covers
Single layer or bubble-wrap type
Doors at one end or both. Slidy or hinged.
Anchor plates for the sides or just pins
Roll-y uppy sides (this is a technical term) for ventilation or ones with mesh panels and a flap. Or not.
Heat shields
Bracing bars for the sides
Integral irrigation bars (like the top brace but with holes in and fitted above where you'd put the beds)
Bars for suppo[/list]rting toms/vines and the like.

My thinking was that maybe the plates would be good in very windy spots. Then again, you could put planks down the sides.and the door type depends on space and location. But as to the ventilation needs, bracing etc - really not sure. Maybe bracing again in windy/snowy spots? But you could do a diy job perhaps? I have a tendency to over-think things!

I too would be interested to know if any of the options are worth paying for.
User avatar
lancashire lass
Legendary Laner
Posts: 6527
Joined: 28 Jun 2007, 15:17

Re: Polytunnel

Post by lancashire lass »

Freeranger wrote:I was hoping someone who knew what they were talking about would answer this query because I looked at them as well, and ended up more confused than I wanted to be.

Options I saw were:


Clear or green net type covers –


Clear covered polytunnels come in different grades – the thicker plastic ones are much more expensive and usually guaranteed to last about 10 years. The price however, is eye-wateringly expensive especially if you are new to polytunnels and just want to try it out first. The thinner plastic can be damaged easily (I’ve seen one completely trashed after a gale force wind), and when it tears, it can split the entire length meaning a full replacement of cover. These type of polytunnels tend to be solid built with a sturdy frame but there is a lot of ground preparation required (trench digging, burying the covers deep and so on) to ensure the wind doesn’t knock it over.

Green checked covers (it is not a net but like a plastic coated fabric – the cover is similar to the garden furniture covers you might use to protect over winter) and also comes in different grades – some covers are cheaper than others, but all wear out more quickly than the clear version. The damage is usually caused by UV radiation from the sun (some plastics degrade in sunlight) and the weak points are where the cover is against the frame. To extend the usage of the cover even though damage will eventually be inevitable, hot spot tape (a spongy sticky tape) is stuck on the frame – this helps to make the cover taut and reduce chaffing from the wind, but also as the name suggests, prevent the metal frame from coming into direct contact with the cover and heating up in hot sunshine.

These type of polytunnels are much cheaper to buy, with the cover placed over a steel frame – if the polytunnel is positioned where it is sheltered from strong wind, they are an ideal type for someone wishing to see if growing in a polytunnel is worth trying. Replacement covers are available (admittedly not cheap compared to when you buy a new polytunnel) There are different types of steel frame – it is recommended to go for the 25mm galvanized steel with the thickest possible tube wall (thin walled tubes will collapse under the first serious wind, and powder coated frames will rust quickly) You can bury the cover much like the clear ones but bear in mind that as covers need to be replaced about 3-4 years, you could instead put paving stones on top.

Single layer or bubble-wrap type
– never tried a bubble wrap type. I have used bubble wrap in a greenhouse for winter insulation and I noticed that it degraded over time quite quickly. However, I’d imagine it must be a different type of plastic that will last longer. I think bubble wrap might be warmer, especially in spring when the sun’s heat warms up the polytunnel and keeps the heat in longer during cold nights (but it would still be wise to have additional heating and protection for overnight frosts or tender plants)

Doors at one end or both. Slidy or hinged
– I would probably recommend both ends as it can get very hot in a polytunnel in midsummer, especially in a heatwave. Summer plants like heat but even they will be scorched / die at temperatures above 35-40oC (a greenhouse / polytunnel can reach much higher temperatures) You can always keep one door closed until it is needed and at least you have an option should the need arise. Slidey or hinged – personally, I think hinged. I have 2 greenhouses with slidey doors and after a heavy frost, the water freezes in the grooves and you can’t get the door open. But then if it is for summer use, perhaps a slidey door would make it more compact (a hinged door banging in the wind can be annoying)
Anchor plates for the sides or just pins
– I really think it depends on where the polytunnel is sited. My garden is surrounded by tall privet hedge and in a natural hollow anyway with fences and hedges in other gardens taking the brunt of strong winds from the south and west, so I found I didn’t need anchor plates and used just tent pegs (but lots of them, and the longer length ones pinning them in opposite directions rather than straight down)

Roll-y uppy sides (this is a technical term) for ventilation or ones with mesh panels and a flap. Or not.
I think the Roll-y uppy sides have mesh panels (and if it is not rolled up, is a flap LOL) and is standard. You definitely need ventilation as polytunnels can get humid (not good for tomatoes as it encourages mould and rot)

Heat shields
– I’ve not seen one with a heat shield but sounds like a good plan. Midsummer sunshine and a heat wave can really ratchet up the temperature very quickly.

Bracing bars for the sides
– I would have thought they would come in the kit (?)

Integral irrigation bars (like the top brace but with holes in and fitted above where you'd put the beds)
– if you want something like that, it’s up to you. I’d have thought a hose pipe (especially if you have a big polytunnel) or watering can would be sufficient

Bars for supporting toms/vines and the like
– the steel frame with green checked covers have bars that run along the length of the polytunnel about 12-18 inches away from the sides - the bars are there to support the cover but which can also be used for tying up tomato/vines and tubing for watering etc.

My thinking was that maybe the plates would be good in very windy spots. Then again, you could put planks down the sides.and the door type depends on space and location. But as to the ventilation needs, bracing etc - really not sure. Maybe bracing again in windy/snowy spots? But you could do a diy job perhaps? I have a tendency to over-think things!


I think you might be overthinking LOL - sometimes it might be a case of try it and see, and make modifications as and when

I too would be interested to know if any of the options are worth paying for.


Sometimes the costs outweigh what you actually get - then again, life's too short and it might be worth buying instead of cobbling something together particularly if you are not a confident diy-er. Not the most helpful answer but it depends if you want to do the job on the cheap just to see if a polytunnel is your thing, or start with a basic then build up to the other gizmos (you might find you have no use for them, then again you might wonder if it will make life easier for you) or splash out on the most expensive polytunnel and just go for it especially if cost is not an issue.

EDIT - if you go for a green checked polytunnel over a steel frame and decide you don't like it, you can always use the frame and cover with mesh for a ready made chicken run.
Last edited by lancashire lass on 16 Jan 2017, 12:46, edited 1 time in total.
User avatar
KathJ
Longlasting Laner
Posts: 934
Joined: 12 Sep 2012, 13:13
Gender: Female
Location: Shropshire

Re: Polytunnel

Post by KathJ »

My other queries seem to be a wooden base or aluminium and to trench or not to trench +f+ I too tend to overthink things and think if you're paying more it must be better which might not necessarily be the case!!
Kath xx

Mum to my beautiful girls Lucy, Holly, Rosie, Hettie, Polly, Ruby, Lily, Penny, Gracie, Maisie, Molly, Evie and my gorgeous boy Toby

RIP my beautiful Ranger, Roxy, Bluebelle, Poppy, Speckle, Daisy and Honey xxxx
User avatar
KathJ
Longlasting Laner
Posts: 934
Joined: 12 Sep 2012, 13:13
Gender: Female
Location: Shropshire

Re: Polytunnel

Post by KathJ »

Thanks Lancashire Lass, a very comprehensive reply (think my last post and yours just crossed!!). Certainly a lot to take into consideration )like(
Kath xx

Mum to my beautiful girls Lucy, Holly, Rosie, Hettie, Polly, Ruby, Lily, Penny, Gracie, Maisie, Molly, Evie and my gorgeous boy Toby

RIP my beautiful Ranger, Roxy, Bluebelle, Poppy, Speckle, Daisy and Honey xxxx
Freeranger
Legendary Laner
Posts: 3171
Joined: 17 Apr 2012, 10:13

Re: Polytunnel

Post by Freeranger »

LL, you are so kind and always give the most incredibly helpful answers. Thanks very much for yet another really helpful answer. Very much appreciated.
Post Reply