Polytunnel Growing

Polytunnel Gardening

Garden-Pride-Polytunnel-3What is a Polytunnel?

A polytunnel is most commonly an elongated semi curcular 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 microclimate 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.

Visit Our Range of Tunnels & Accessories Here

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.

polytunnel-gardenWhat 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

polytunnel with raised bedsGrowing 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.

Bayer organic pest controlPests 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.

Here are some Organic pest control products that are safe to use on edible plants:
Bayer Organic Pest Control Spray
Garlic Wonder pest spray concentrate
Growing Success Organic Slug Killer

envirogrind peat free soil improver

Avoid peat based composts or soil mixes as peat tends to encourage certain pests. Try some of our peat free composts here:

GroChar Seed Compost 8 Litre
GroChar Multipurpose Compost
Lady Muck Organic Manure
Bulk Bag Of Organic Compost

    1. admin

      Hi Di

      That is a difficult question to answer as it depends what is growing in the tunnel. Also, the temp and humidity will fluctuate wildly depending on outside temperatures and amount of direct sunlight. In general I would leave my Tunnel open from mid May to August unless it is unseasonally cold. As a rule of thumb I would not let the temp exceed 30 degrees C for long periods though on very sunny days this may be unavoidable. I hope this helps. Andrew

  1. Susie Thompson

    Hi there,

    I have a poly tunnel of 20ft x 56ft so a good size! Next Spring I would like to grow some bedding plants/annuals for hanging baskets but most seeds need to germinate at around 20-25 degrees. As I would like to grow more than just a few dozen, would you have any advice on heating a section of the tunnel or anything else as I don’t believe the tunnel would get to those sort of temperatures until after I would like to sow, I would really appreciate any advice/ideas you could offer.

    Thanks Susie T

    1. admin

      Hi Susie. That sounds like an impressive tunnel! I am not an expert on flowering plants but expect the temperatures you mention might be on the higher end of what is required. There are a number of solutions to heat germinating seeds ranging from the airing cupboard to purpose built electric propagators. If you will be doing a lot of propagation for both your flowers and vegetables and enjoy your hobby it might be worth getting a good propagator. The best one on the market is the Vitopod which we like because it has the ability to add extra layers to accommodate the height of growing plants. It also has a very accurate and easy to use thermostat which keps the temp inside the unit exactly as you set it. I include the link to the 2 sizes here: https://www.quickcrop.co.uk/search/vitopod We also have cheaper units which you can view in our propagation dept here: https://www.quickcrop.co.uk/propagation Please let me know if I can be of any more help. Andrew

  2. Chris harry

    Hi, I’ve just made a 3.6m x 3m frame out of 32mm blue water pipe,what I do need to know is what is the best grade of polythene to use for my polytunnel and also any recommendations where I can buy it

  3. Hasanka harischandra

    That is good article and this is first article i rod fore my itersting to grean house and poly tunnel
    Thank you

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