Having a greenhouse or polytunnel means that you can grow vegetables and fruit that would normally not be suitable for our UK weather.
As both will increase the temperature within them, you can start growing earlier and for longer, which means you can grow more crops and increase your yield. So you can have homegrown tomatoes even in cold weather.
So every vegetable gardener will be keen to have either in their garden. But which one is the better option, a greenhouse or polytunnel?
The answer is, it depends on what you need and want. To make your decision a bit easier, we have pulled together the main facts about greenhouses and polytunnels. Knowing the advantages and disadvantages of both will give you a good knowledge base to make the best decision for your needs.
The Difference Between A Polytunnel And A Greenhouse
The first thing to point out is that they are both used for the same purposes, these include:
- to grow fruits and vegetables all year round
- to prolong your growing season
- to grow exotic plants that would normally not survive in the UK
- overwintering plants vulnerable to cold
- starting off plants from seed
This is achieved by creating the right conditions for plants to thrive independent of the weather conditions outside.
The main difference between greenhouses and polytunnels is the material they are made of. A greenhouse is made of glass, whereas a polytunnel is made of a sturdy plastic sheet.
A greenhouse has a frame which is made of metal (such as aluminium or galvanised steel) or wood. Glass panels are inserted into this frame. It’s basically a glasshouse, another name used for it. Nowadays, you can also get polycarbonate greenhouses. Their panels are made of polycarbonate, which is plastic.
In contrast, a polytunnel consists of a metal frame over which a strong plastic sheeting is laid, which is dug into the soil.
While both come in different shapes and sizes, polytunnels, as the names suggests, are normally tunnels. A glass greenhouse is normally square.
Because they are made from different materials, there are differences when it comes to the main aspects, such as heat retention, temperature regulation and cots.
In our quest to help you to decide if a greenhouse or polytunnel is better for your needs, we have drilled down into the different aspects to give you a clear picture of the differences.
Costs
Let’s start with one of the main consideration for most people. Which one is cheaper, a polytunnel or greenhouse?
The answer to this question is simple, the polytunnel. This is mainly due to the material costs.
A small polytunnel, which can cover a bed with lettuce or strawberries, can cost less than £10 pounds. A bigger walk in polytunnel can be purchased for around £50. If you want a good quality one, £200 – £300 will get you a good-sized polytunnel of good quality.
Even a small greenhouse will set you back around £200 and a big one could cost you over £1000. And you can go as high as several thousand pounds.
The bigger you need, the bigger the price difference. This means, if you want a big growing area, a polytunnel is definitely more cost-effective.
So, if you are on a budget, a polytunnel might be the better option for you. So if cost is your main consideration, whether to buy a greenhouse or polytunnel, the polytunnel comes out on top.
Durability
When it comes to cost, durability plays its part. Because the longer you can enjoy your polytunnel or greenhouse, the better is the value for money ratio in the long term. But which one is more durable, the greenhouse or polytunnel?
Generally, it is said that a greenhouse is more durable. Which is true to an extent.
A greenhouse can last for a lifetime, but you will have to keep it in good repair and the glass panels will need replacing from time to time. This will have a cost attached to it.
If the structure of your polytunnel is of good quality and well maintained, it can also last a lifetime. But the cover won’t. Every 5 years or so, you will have to get a replacement cover.
The cost is probably comparable to the cost of changing class panels in a greenhouse, so there isn’t that much between them.
In one respect, the greenhouse does have the upper hand though. And that is their endurance of extreme weather. A greenhouse, with its toughened glass, will be able to withstand strong winds much better than a polytunnel.
So, if you have a very windy site, then the question between greenhouse or polytunnel might be answered in favour of the greenhouse.
Space
Another big consideration is how much space you need. A polytunnel can offer more growing space, so if you want to grow as much as possible, then a polytunnel is the better option.
If you only have a small garden, a polytunnel might look out of place and overbearing. You might be better off getting a small garden greenhouse, such as a mini greenhouse.
So the space you have available will play a big part in your decison to buy a greenhouse or polytunnel.
Installation
Building a greenhouse can take quite a while and can be quite a complex task. You can, of course, get it installed by experts, but this will add to the cost.
On the other hand, commercial polytunnels are simple to build and won’t take long to put up. You can do it easily in a day, if you have a helper.
Another aspect of the installation is site preparation. For a greenhouse, you need the ground to be level and even. Otherwise, you could get yourself into a pickle.
While a polytunnel will benefit from a level ground, it’s not that important. And you can even put one on a slight slope, if the best spot in your garden or allotment is not on even ground.
What you can do with a polytunnel, but not a greenhouse, is to move it. A greenhouse, once installed, will stay in its allocated spot. Or at least it will be rather difficult to move it. With a polytunnel you have the freedom to move it as it suits you.
If installation and movability is your biggest concern when buying a greenhouse or polytunnel, then the polytunnel has more advantages.
Heat Retention
One of the main purposes of getting a glass greenhouse or a polytunnel is to provide a warm environment for your veggies. So looking at how well the two actually retain heat is important. But which does it better, greenhouse or polytunnel?
In this category, the greenhouse comes out on top. Glass is much better at retaining heat than a plastic sheet. So, if you need a very warm space to grow exotic plants, then a glass greenhouse might be the right option for you.
A polytunnel will retain heat, but not to the same level. Depending on how cold it gets in winter where you are, you might need to take extra measures, if you overwinter them in a polytunnel.
However, if you want to extend your growing season or grow winter vegetables, both will be suitable.
Light Transmission And Shading
A greenhouse will allow for more light transmission, which is good, but can also make it very hot in summer. We managed to burn our seedlings one spring, because we were surprised by an unusual warm day.
Not all plants will do well in direct sunlight though, so providing shady spots in a greenhouse for plants that need it, is important. But which one does it better, greenhouse or polytunnel?
You can paint some glass panels or install blinds. We opted for the second option after our disastrous spring day. You can also use shade cloths. Find out which are the best shade cloths for greenhouses in our review.
The polythene sheets don’t let as much light through as glass. Most polytunnels come in two colours, clear or green. A transparent cover will let more light through, so if light transmission is essential, choose a clear polytunnel cover.
Glass can also produce hot spots, by focussing the sun’s rays, which can cause problems. The polythene sheet, on the other hand, diffuses the sunlight, so it provides a more even coverage.
A polytunnel will also not get as hot in summer as glasshouses, which gets us nicely to our next point…
Ventilation
To avoid your plants getting too hot, it is vital that you can ensure good air circulation.
In a greenhouse, you can leave the door open or open windows. Some even have the ability to open the windows when a certain temperature is reached. Of course, this comes with additional costs.
Depending on the size, polytunnels come with flaps that can be opened or with doors. Ideally, you want a door at each end of the tunnel, so you can open them both to allow for air to flow through.
In this category, both perform equally, as they will give you the opportunity to allow for ventilation. So, greenhouse or polytunnel, you will be able to provide your plant with good air circulation.
Looks
Most of us don’t just have gardens to grow fruit and vegetables in, but also to relax and enjoy the warm summer months.
And our houses also overlook our gardens, so whatever structure we put in them, we should keep how it will look in mind.
Greenhouses come in various designs and can look beautiful and create a lot of interest in our garden. The Victorian Style is especially popular as it gives your garden a distinguished look.
A polytunnel on the other hand, is not that nice to look at.
This is a pure question of preference, and you will have to decide how important appearance is for you.
So now that we have shown you the difference between both, you should be able to decide what suits you better, a greenhouse or polytunnel.
If you are now keen to get your own polytunnel or greenhouse, here are some that we would recommend. And because they are available on Amazon, you can start growing in no time.
Birchtree Polytunnel
- Dimensions: 4 x 2 x 2 mm (L x B x H)
- increases the moisture, controllable environment by heating and cooling
- protection against extreme temperatures
This walk in polytunnel is great, as it has two doors, which means you can ensure that your plants have good air circulation.
Because the cover is green, your plants won’t have to endure extreme temperatures.
The frame is made from galvanised steel, which means it is more rust resistant and will last you a long time.
Outsunny Polycarbonate Greenhouse
- 6ft x 4ft open design: A greenhouse with a generous amount of space - giving plenty of room for your plants, vegetables, flowers and more to grow. Fit with shelves, planters - whatever you want.
- Aluminium frame: A strong core structure for this greenhouse. Fitted with rain gutters to naturally catch water.
- Polycarbonate panels: Creates a safe shelter inside, shielding from wind and rain - helping plants grow! Transparent to allow sunlight through for much-needed nourishment.
This greenhouse is made of polycarbonate panels, so is cheaper than a glass greenhouse, but still as effective.
It might not look as fancy as some others, but the price is affordable, and it has some important features.
To avoid overheating, you can open the door as well as one of the top panels. This will ensure good air circulation.
The frame is made of rust-resistant aluminium, which means it will last for a long time.
It also has an integrated rain gutter to keep the roof free from standing water.
Now, all you have to do is to decide if you want a greenhouse or polytunnel.
If you are all keen now to get growing, read our growing guides to get ready. You can learn to grow tomatoes, courgettes, potatoes, lettuce and much more.
