Here's why you should be using a polytunnel to boost growth

Published 23rd June 2022
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With a growing interest in gardening and outdoor livinggreenhouses are becoming a vital addition to any keen gardener’s plot - and polytunnels are among some of the most popular types you can find! 

Here at OnBuy, we have an extensive range of greenhouses and cold frames available, including plenty of polytunnel models that are sure to suit your needs.

Discover exactly why a polytunnel could be the perfect addition to your garden here.


What is a polytunnel?

A polytunnel (or tunnel) greenhouse is an elongated outdoor frame that’s covered with polythene sheeting (under which seedlings and plants can be grown).

They’re available in multiple shapes and sizes, each creating its own microclimate for the vegetation underneath.


What are the benefits of polytunnel greenhouses?

One of the main advantages of tunnel greenhouses is the opportunity they present to grow fruits and vegetables that wouldn’t naturally grow in the British climate, such as peaches, melons, and citrus fruits. 

But that's not the only reason why they're so popular!

Other benefits include: 

  • Easy to install and low maintenance - Once erected, they can remain in place for several years, meaning your crops can crow uninterrupted for years to come.

  • Multi-functional - Just like wooden greenhouses, the inside space can also double up as extra storage for your garden furniture, and can even be used to dry your washing!

  • Customisable - If you’re into hydroponic greenhouse systems, you can easily incorporate one of these inside your polytunnel, to maximise the variety of plants you can grow.

How do polytunnels work?

Polytunnels are covered in polythene sheeting, which performs like a traditional greenhouse material by trapping the sun’s rays inside. This causes the plants to transpire, resulting in a slightly more humid environment. 

This warmer air is contained within the structure, creating a microclimate to encourage plant growth.

As a gardener, you have the ability to manually control the temperature and humidity levels by using specialised heating equipment, or by adjusting any vents on the structure.


Is it better to use a polytunnel or glass greenhouse?

There are many different types of greenhouses on the market that all do similar jobs, so it's not always easy to know which is right for you. You can learn more about the different types and who they're right for with our greenhouse buying guide.

You may be stuck between choosing a small polytunnel greenhouse or a traditional polycarbonate greenhouse with glass panelling. While they may seem very similar, there are some fundamental differences that you should consider when deciding which option is best for you. 

The biggest of these is cost: polytunnels are fantastic structures and are better value compared to greenhouses. They are an extremely affordable, convenient way to shelter your entire growing space, so are perfectly suited to both commercial and domestic growers. 

Polytunnels are also much easier to customise than glass greenhouses, which tend to be more permanent once erected. Unlike their fixed cousins, you can also move small polytunnels to different areas when needed, as they don't require a flat base.


What’s the best location and orientation for a polytunnel greenhouse?

As with most greenhouses, particularly walk-in models, the best location will very much depend on the amount of space you have in your garden. For maximum efficiency, it’s usually best to calculate the area of your plot, and then try to find the biggest greenhouse that’ll fit into it. In terms of orientation, it’s a good idea to face your polytunnel greenhouse from a north-to-south direction. This will help to ensure that taller crops create equal amounts of shade on either side during the summer months, and stops them from overheating. 

It’s also worth thinking about the slope of your garden. For the best results, it’s wise to place your polytunnel up-and-down any slope. This will allow for more convenient access for you, and will make watering so much easier (as beds that transcend a slope are much harder to water and mulch).


How long will a polytunnel greenhouse last?

Polythene needs replacing every five to eight years, depending on how windy the site is, and how tightly you stretch it over the frame. As such, it’s probably best to put the cover on in the warmer seasons, as this makes the polythene much easier to stretch. 

Shop our range of polytunnel and tunnel greenhouses to find the perfect home growing accessory that will last for years to come!

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