What is a Polytunnel?
A polytunnel is most commonly an elongated semi circular shaped tunnel made out of polyethylene. They come in a wide variety of shapes and sizes. In functionality they fall somewhere between a garden cloche and a greenhouse, a cloche is used for the same effect with single plants while a greenhouse is much larger and often made out of glass. The polytunnels main use is to create a sort of micro-climate that provides higher temperatures and humidity allowing you to grow various fruit and vegetable plants even when they are out of season. They are also an excellent form of crop protection, protecting plants from heat, cold, wind, rain and strong sunlight. Another major benefit of having a polytunnel is that they are not a permanent structure and can be moved about or taken down completely, quite easily. Smaller polytunnels or hobby tunnels can be used as a kitchen garden for herbs and salads, and larger ones can be used for anything, from growing entire vegetable crops to plant and flower nurseries.
Why Use a Polytunnel?
Most importantly, a polytunnel will enable the gardener to grow fruit and vegetable plants that they would otherwise be unable to grow in their climate. They also extend your growing season so you can grow your favourite foods all year round. Temperatures, humidity, irrigation and ventilation can all be easily controlled via the wide range of polytunnel equipment commonly available. Polytunnels work out much cheaper to buy, maintain and install than greenhouses and are quite easy to put up and manoeuvre yourself. The polyethylene or polythene film most commonly used biodegrades naturally over a long period. It will generally last between 3 to 10 years depending on usage and site etc, before needing replacement.
What To Grow in a Polytunnel
Basically all kinds of flowers, fruit and vegetable plants can be grown. 80% of all soft fruits on the market are grown in polytunnels.
Here is a list of plants commonly grown in a polytunnel: tomatoes, strawberries, potatoes, cucumbers, peppers, salad greens, radish, carrots, melons, cauliflower, lettuce, chillis, peas & beans, cabbage, oriental salads, onions
Growing in a Polytunnel
First off you need to think about positioning. Polytunnels need:
- Flat, even ground
- Access to a decent water supply
- A nice sunny area with some shade (next to a wall or hedge)
- Try and position it N/S instead of E/W to minimize the amount of direct heat from the sun.
Most polytunnels are spacious enough for two rows of raised beds inside, this is ideal as you won't have to walk over good soil to tend plants. Use good quality soil. Raised beds make it easy to maintain a good soil structure. Try and alter your sowing dates to maximize your polytunnels output and to ensure there is always something to harvest.
Pests in the polytunnel
Polytunnels offer excellent pest protection for crops, but you can never be 100% pest free. As a preventative measure keep your tunnel well ventilated and try to maintain a nice even temperature. Too humid an environment can be a breeding ground for pests and diseases, so water well without over watering.
Avoid peat based composts or soil mixes as peat tends to encourage certain pests. Try some of our peat free composts here: