Polytunnels – unlike greenhouses, have an extremely similar construction and shape, regardless of what type you actually buy. Invariably they are based on a hoop structure, with some having the hoop going all the way from the left hand side to the right hand side, and others which have straight sides. These tend to be the larger polytunnels, which gives people the opportunity to decide whether they wish to have the polythene covers go to the ground, or in fact introduce some form of netting to the side. This of course gives flexibility, and the option of diversifying the growing medium that you want to use in your polytunnel.
The temptation (as for anyone who is looking into buying anything – and not just polytunnels) is to just say “Right. Ok. I want to buy a polytunnel – Let’s go and buy one”. However, it is worthwhile having a look to see what options are available and how those options fit in with what you want to achieve from your polytunnel ownership. The last thing you will want to do is to buy a product which is unsuitable, or does not quite meet your needs.
The basic structure of any polytunnel is very simple. It is a row of hoops, which are attached in some way, shape or form to the ground either on a solid structure or, as in the case with most people, various poles in the ground with anchor plates. There can be door entrances at either end of a polytunnel, with the majority of people choosing one larger entrance at one side, with the option of a smaller entrance, or no entrance at the rear. Again, this does depend upon the size of the polytunnel. Smaller polytunnels do not necessarily need two doorways. Also, the introduction of any door facility in a polytunnel increases the price.
The Type of Structure of your Polytunnel
1. It is probably a beneficial way of securing your polytunnel if it is a small structure, say under 12 to 15 foot long, but any more than this and you will be spending several hours of hard graft with a pickaxe or a mattock digging out a suitably sized trench.
The other problem tends to be that when you place your polythene into the trench, it can leave some degree of wrinkle in the cover itself – which can be unsightly. However, with two people, this can largely be avoided. The polytunnel that we have at present has no polytunnel crimp.
2. You can use base rails that basically attach the polythene to the polytunnel structure, rather than the outside earth area.
The big negative with regards to this is that it does lose some of its support and stability that trenching-in your polytunnel cover will give you. With the use of anchor plates however dug in at each corner, or even with each hoop, only hurricane force winds will shift the polytunnel. Therefore, I do not see this as being a deal breaker. Whilst I have not used or seen the structure in operation, I understand that it can be a little fiddly, and certainly requires two people to attach the polytunnel cover (regardless of the size of the polytunnel itself) in order to avoid kinks. This is however offset against the back-breaking work of digging out and filling a trench so this must be an excellent option to consider.
3. Solar Polytunnels. This form of polytunnels can be considerably more than the cost of a traditional polytunnel and there are specific manufacturers who offer this type of product. They differ from the traditional polytunnel, in that rather than being wrapped in a single sheet of polythene, the tunnels are clad in modular sections which attach. This is probably a split between a greenhouse and a polytunnel – and it is certainly an option, as they provide the structure of a greenhouse without the potential damage should any of the glass break. However, it is at quite a hefty price which, whilst not so much as a greenhouse is, it certainly is far more than a polytunnel. Therefore, I would be inclined to stay with a polytunnel itself.
4. Self-build Polytunnels. You can never build your own polytunnel yourself of course, but you can obtain poles from a variety of sources (such as ebay or Gumtree) and look at then purchasing a cover independently with one of the many polytunnel manufacturers. Even the main structures can be purchased in parts from a lot of manufacturers. If you have purchased a variety of poles and are missing some elements, they will supply various articles (obviously at a cost to you). When we bought our property that we are in now and looking at a polytunnel, we did in fact inherit an existing polytunnel, which we moved. Of course, in moving this, the polythene was no longer usable and that was sort of a second-hand purchase. However, whilst this might be a saving at the outset, you have to consider the time in finding a polytunnel from whatever source you can locate and, because you are buying it from a third party, it is not something that you have ordered – it will not necessarily be to the specifications that would fit you and your plot.
We have to all consider that, as gardeners, we are very particular about how we structure our gardens. Bearing in mind how important polytunnels and greenhouses are, buying second-hand can be cost-effective – but does it really fit in with what you want to achieve and how you want to achieve it?
Saying that, and going against what I have just said, when I replace one of the polytunnels, I will actually be using the various bars with fruit netting to cover our fruit garden (which is an unusual size and shape) and the poles themselves will provide an excellent soft hanging perch for the netting – coupled with a timber structure. So, in the traditional gardening sense, yes – whilst some items we all like to look at buying new to fulfil a specific need, we do however like to adapt as gardeners, and use whatever we have in the best way possible, so therefore recycling anything is always a good thing.
Moving on from the type of structure that you may want to buy, you can then look at the various options that are available to you within this particular format, mainly what size polytunnel do you want? There are three main types of polytunnel (with regard to the size) which are regular, semi-commercial and commercial.
The regular polytunnel is a size of approximately 3 to 4 metres wide. It comes with an option of a couple of different sized aluminium poles where the structure can run for as long a distance as you would like, but probably no more than 20 to 30 feet. This is an ideal product for the vast majority of gardens and for those people who have space which is a premium, and do not want a large structure to impact on their plot too much.
Again, this can start off with any particular size, but generally speaking, the width would be 4 metres plus and will run for anything up to 50 to 60 feet in length. Again, there is usually an option for pole thickness for additional stability, but with regard to the options – do not go for the smaller one as by the nature of the product, it is going to be a larger structure and if you can supersize the pole, it is always the best thing to do.
Commercial polytunnels are, as they state, large structures which we would normally see at small or even medium sized garden centres and they offer a fantastic growing medium but for the vast majority of people it is always worth mentioning this size of polytunnels, but to be perfectly honest if this is something that you are after, then you have a larger operation than I have and you are looking at making significant use of your plot and growing considerable numbers of plants either for commercial sale or consumption of a small army. Due to the nature and structure of any commercial polytunnel, it will be erected by a specialist team and not just a couple of people with a wheelbarrow and a pickaxe.
The choices of polytunnels, and of course the internal apparatus that can go into a polytunnel, is vitally important. It is important to research the correct product and internal workings that make sure that you can utilise (to the maximum possible extent) your garden operation. For my needs, a semi-commercial polytunnel will be perfect, as it not only provides the size of structure that can fit into the location that I have in mind, but it also offers an excellent growing medium and size that will enable me to maximise bringing on plants in the winter months for the garden, and also to grow vegetables and some fruit in the summer months.