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Do Polytunnels Need Ventilation?

Do Polytunnels Need Ventilation

Polytunnels are a popular choice for growing crops and can be useful in many ways. A timber ventilation rail is a traditional option, but you can also consider installing a polythene blind. This enables you to roll the ventilation closed when needed. This will allow you to control the ventilation according to the type of crop you are growing and the amount of moisture you are producing.

Proper ventilation

Polytunnels require extra ventilation, especially if they are longer than 20 metres. This can be achieved with side ventilation systems, which come as complete kits with aluminium fixing rails and side aluminium gutters. These systems also come with a wide mesh netting to keep the roll up curtain in place.

Controlling humidity

Controlling humidity in polytunnels is a crucial aspect of growing plants in these structures. Different crops require different levels of humidity and temperature. This can be achieved by controlling ventilation and changing the planting scheme. Proper ventilation is also essential for preventing plant diseases.

Temperature measurement

Polytunnels are structures that are designed to allow farmers to grow crops at controlled temperatures. They are similar to greenhouses and cloches, but with the added benefit of allowing machines to be used for sowing and harvesting. They have been used extensively in plant nurseries and floriculture, and are now being used for livestock housing as well.


There are a few ways to insulate a polytunnel. You can use bubble wrap as an insulation material. You can fasten the bubble wrap using string or cable ties. It is important that you choose a UV stabilized bubble wrap.

Light transmission

There are many factors to consider when it comes to determining the correct light transmission in a polytunnel. The plastic covering on a polytunnel is an important aspect. Light transmission decreases as the cover ages, especially when exposed to sunlight. Many polytunnels have UV inhibitors to prolong their life. They also contain EVA (ethylene vinyl acetate) for increased strength and flexibility.


Ventilation is a vital component of any polytunnel for a variety of reasons. Not only does it aid in photosynthesis – the process of plant growth by absorbing carbon dioxide from the air – it also helps keep plants cool. However, the type of ventilation you need depends on your needs and your location. For example, polytunnels in the Highlands of Scotland are unlikely to need as much ventilation as polytunnels in temperate climates.


Polytunnels are great for growing plants that are difficult to grow outside. Most of these plants are annuals and perform much better inside than outdoors. For instance, asparagus and globe artichokes grow very well in polytunnels. These crops are easier to cultivate and can be used in many more recipes than they are outside.