Choosing and Setting Up the Perfect-Sized Polytunnel

Small polytunnels are either semi-circular or square, and elongated shape by their various length dimensions, the curved hoop ones are generally for garden and allotment suitability having limited headroom, and the straight-sided option offers more headroom height and walk-in without bending. Normally, comes with clear or diffused polytunnel coverings.

These structures are composed of hoops with transparent or diffused plastic sheeting over the top, serving as excellent and capable shelter housing for maintaining and providing protective and stable crop temperatures, allowing for various seeds, cuttings, and plant storage to thrive. They come in various size kits or can be bespoke built and can be used for varying cultivation purposes, growing crops, extending growing seasons, and providing adequate protection for wintering plants, alongside storage, or small animal and fowl shelters.

Selecting the best option depends on the individual's cultivation requirements.

Sizes of small polytunnels come in a wide range of sizes and dimensions, from compact 2-metre wide makes and models ideal for seasonal tomato cultivation to larger 18-metre structures and various length dimensions to suit your garden’s individual space. Suitable for year-round crop production and plant storage depending on cover materials used for the location of the structure within the UK.

For specialised growth and extended harvests, you can opt for forcing tunnels, which require thicker, stronger, hardier materials to be used as polytunnel coverings. The choice of size depends on your cultivation goals and the available space.

 Cover Options:

Polytunnel covers vary in material type and purpose. Different options such as Anti Drip and Anti-Fog, thermal screens for enhanced insulation and heat retention, light-diffusing covers for even light distribution, or reinforced or heavy-duty models for added protection, strength, and durability. The polytunnel coverings that are now available should ideally be fit for purpose, and the choice should align with your crop preferences and environmental conditions.

Materials Used Matters:

The components used in various kit makes and models of small polytunnels, play a crucial role in their performance and capabilities.

Polytunnel Hoops: Typically made out of aluminium, galvanised steel, or hard plastic, these form the tunnel's frame structure. Weather resistance is essential, and the frame material should have a diameter of at least 10 mm. Tension struts can also be used.

Base Rails: Ensure your polytunnel is securely anchored to the ground to prevent wind and movement damage. Smaller structures may require basic stakes or sandbags, this is all down to cost and preference, while larger ones, benefit from ground anchor stakes, concrete blocks, and base rails or grommet fasteners.

Polytunnel Covers: The material's thickness, typically measured in microns or grams per square meter (g/m²), affects longevity, strength, durability, and insulation. Thicker gauges and double-lined covers provide better protection and longer life expectancy.

Polycarbonate Panels are used by year-round producers who require certain use capabilities: These thermoplastic clear panels, though more expensive, offer superior durability, insulation, and UV protection. Resistant to water and certain impact damage. They often come with longer warranties.

Other types of manufactured coverings include Fibrolux, a corrugated shape with additives including glass fibre.

Synthetic Polyglass sheeting can be bent into certain shapes such as an arch shape and cut to size using appropriate cutters and screwed to attach.

Pyglas offers good resistance to atmospheric and chemical wear.

Doors: Choose between hinged or sliding doors or cut-outs in the cover that can roll up and down. Ensure the door's width accommodates easy passage with equipment.

Air Vents: Consider lateral air vents to regulate airflow and sunlight, promoting healthy crop growth conditions.

Pros and Cons

Small polytunnels are cost-effective, quick, and easy to assemble, and allow for efficient use of the underlying soil. They typically do not require planning permission for domestic use.

Temperature disadvantage. Compared to glass or polyurethane greenhouses, polytunnels may not be as visually appealing and can sometimes take longer to heat up. They are not always suitable for installing heating appliances and are less weather-resistant unless reinforced.

Size and Installation Location

Determine the polytunnel size based on your gardening goals and available space. A rule of thumb is that a polytunnel should cover approximately one-tenth of your overall growing area. Whilst smaller polytunnels offer better temperature control, larger ones can hold and produce more plants and varieties.

Choosing the Location: Select a location free from obstructions like trees or uneven terrain. Account for prevailing wind direction; avoid placing any type of small polytunnels to face strong winds. Proper placement ensures efficient air circulation and minimises the risk of damage. By understanding the above factors, you can maximise the benefits your polytunnel offers, while efficiently and effectively growing crops or plants. Make sure your intended uses, for the polytunnel coverings meet both your and the crops' demands. Check the local area for any regulations before erecting your structure to ensure compliance.

Read More:

Polytunnel Refurbishment: The Expert Touch 

Polytunnels: The Ultimate Producers of the Fresh Produce