Polytunnels and greenhouses enable anybody growing plants to manage light conditions. They also protect plants from wind and other weather conditions. But even though the words polytunnel greenhouse are often used together, they are very different structures.
If you are looking for a structure that will protect your plants and enable you to grow them under cover, which will you choose? In these garden tips, we’re going to show you the pros cons, and other features of both. Your needs, including your budget and the space you have available, will determine whether you choose a polytunnel or a greenhouse.
What is a polytunnel?
A polytunnel is basically a utilitarian version of a greenhouse. It’s cheaper, easier to erect, and pretty well as effective as the traditional greenhouse.
Polytunnels were developed primarily to meet the challenges of food production. Although mostly used by farmers, they can also be used on a much smaller scale by home growers.
Of course, polytunnels don’t look anything like greenhouses even though they have the same basic uses. Sometimes called hoop houses, they are basically steel-framed tunnels constructed with a polyurethane cover.
Despite the differences, polytunnels work much the same way as glass greenhouses. Essentially, they become a climate-controlled environment that you can use for growing.
Polytunnels are a relatively recent invention, although the first very basic ones date back to the 1940s. Their development has been reliant mainly on the development of plastic materials.
Polyethylene is what has made polytunnels more accessible and increasingly popular globally. One of the attractions is that they can be constructed in a wide range of sizes. This makes them suitable for both commercial and backyard use.
What is a greenhouse?
Greenhouses go back to the 17th century when they were constructed from timber or brick. They had substantial glass windows and were heated.
Their popularity peaked in Victorian England in the 19th century. But since then, their appeal has spread worldwide.
Victorian greenhouses, or glasshouses as they were also known, were made with a timber or metal framework and were wonderfully decorative. Over time they have become more basic in look, but the functionality has remained the same.
Essentially greenhouses have always been working buildings. Traditionally they were used on large properties when a skilled gardener was employed to look after the plants.
Gardening under glass was a big thing in the Victorian era. They were either built as freestanding structures or lean-tos that incorporated one wall of the house.
The main intention was heat retention, which has carried through to polytunnels.
Modern greenhouses are a bit different. Some contemporary greenhouses are even built using transparent plastic sheets or even fiberglass. But these are rigid as opposed to the polyethylene used for polytunnel greenhouse-type structures.
Whatever material is used, it should extend to ground level, at least on one side, to allow the maximum amount of sunlight to enter.
Difference Between Polytunnel vs. Greenhouse
Polytunnel greenhouse. Two words that describe structures that can both do more or less the same thing.
But from the descriptions above, you can see that they are very different structurally and visually. Functionally they are much the same.
In reality, nowadays, farmers will use polytunnels to grow large quantities of fruit and veg. Those who grow tropical fruit and classic or exotic flowers are more likely to use a greenhouse.
That doesn’t mean that you can’t use a polytunnel at home if you have the space. It also doesn’t mean that commercial growers of tropical fruit and classic or exotic flowers won’t use polytunnels for their businesses.
In fact, there are many suppliers of polytunnels who promote their products as large plastic greenhouses. If you look at them you’ll realize immediately that they are nothing like traditional greenhouses, but you’ll get the same results. That is unless you want a traditional greenhouse that adds a certain style to your garden.
There’s even a research study that looks at “production greenhouses and polytunnels” all in one breath. Published in March 2022, the paper focuses on the management of sunlight in these structures.
But, to be honest, it’s more about similarities than differences. There is no doubt that both polytunnels and greenhouses will buffer the natural fluctuations in heat, cold, and light. It’s that simple.
Polytunnel vs. Greenhouse: Pros and Cons
Greenhouses, polytunnels, and other shade-houses all protect plants from too much sunlight as well as the other detrimental effects of weather. But what pros cons and other features do polytunnels and greenhouses offer?
Pros and cons of polytunnels
Polytunnels are usually made using a series of metal hoops that are covered with transparent plastic.
They can also be covered with shade netting, but you won’t achieve the same effect as you will with plastic because the netting is breathable. Shade netting on the other hand is great in hot climates because it reduces the intensity of sunlight and heat.
Polytunnels are cheaper than greenhouses per square foot. This is simply because there aren’t any design features and the materials used are cheaper.
They are generally available in a range of sizes to fit small and large spaces. Typical width sizes are 10, 14, and 18 feet. Length may be anything from 12 to 90 feet.
They are also available in a few different styles, straight-sided and curved, in kit form. While the original polytunnel designs were curved, straight-sided tunnels make it easier for those working in them to stand up straight at the sides and in the middle.
You don’t need skilled workers or specialized tools to erect a polytunnel. They are also lightweight, which means they are easy to work with.
This also makes them versatile. While not effortless, you can move a polytunnel between locations if you need to.
Most polytunnel kits can be erected by 2-3 people. Most include all the clamps and fixing parts you need, but door frames are usually sold separately.
The quality of polytunnels varies. So, if you buy a cheap product you run the risk of weather damage, especially if you live in a windy area.
A good quality polytunnel covered with polythene will have an expected lifespan of 8-10 years.
Pros and cons of greenhouses
Today, greenhouses are usually constructed with a metal frame and either glass or rigid plastic material. It stands to reason that the design and materials used for construction make them more expensive than polytunnels.
They aren’t quite the same as traditional greenhouse structures, but modern greenhouses are still more aesthetic than polytunnels. They are also relatively heavy, permanent structures that need to be properly constructed.
Like other garden buildings, greenhouses often have sloping roofs. When built as a lean-to, the roof will only have a single slope.
Building a greenhouse with glass rather than rigid plastic adds to the cost. It also increases the risks of breakage because walls and roofs are usually glassed.
Like polytunnels, they are also available in kit form, which simplifies the construction aspect. Greenhouse kits aren’t usually made with glass, which makes them an appealing option.
Sizes are much smaller than polytunnels, which is an obvious advantage for most homeowners. Sizes depend on the manufacturer, but as an example, they may be 6 x 4 feet, 6 x 6 feet, 8 or 10 x 12 feet.
A properly made greenhouse may also be heated, not only by the sun but also by artificial means. This, of course, can make it very hot and so ventilation is also needed, usually through openings in the roof. Sometimes they are automated, but often need to be operated manually.
Some greenhouses have openings in their end walls. Electric fans can then be used to circulate air inside.
What’s the best choice for you
Greenhouse polytunnel. Which one is the best choice for you?
It depends entirely on your needs. How much space do you need undercover?
What is your budget? What is the availability of products and/or materials in your area?
Before you decide, find out whether your local council has any regulations that relate to polytunnels or greenhouses. You may need plans for a greenhouse and planning permission for a polytunnel.
In some areas, these structures may not exceed a certain percentage of the plot and their height is restricted. If you are using them for homegrown food and not commercial use, you may not need any form of permission. But check before you buy and/or build.
There are similarities between polytunnels and greenhouses, but there are also vast differences. Greenhouses have been used for centuries, while polytunnels are a relatively new 20th-century invention.
They both provide a suitable microclimate for growing food crops, flowers, and other plants. And they can both be used by farmers and home growers on just about any scale, depending on space.
Polytunnels are considerably cheaper than greenhouses, even when these are constructed using transparent plastic instead of glass. But greenhouses are better looking and, imaginatively constructed, will add visual appeal and a certain sense of style to any garden space.
Polytunnels are totally utilitarian and functional.
Ultimately, the choice is yours.