It’s very exciting when you have finally saved up for the polytunnel you have dreamed of. However, buying a polytunnel for the first time can be an overwhelming and confusing experience. As with any purchase there are a few things to consider.
Choosing the right polytunnel size Once you have decided where your polytunnel will be sited, you can decide what size you need. Don’t regret purchasing a polytunnel that is too small always go for the largest you can accommodate.
Steel diameter Always ask the steel diameter a company is providing. The diameter of the steel can range anywhere from 25.4mm up to 38mm with some even offering 50mm. This could be the difference between a polytunnel that will last a few years and one that will last a lifetime.
Hoop spacings Polytunnels can be supplied with different hoop spacings (distance between each hoop). The closer together they are the stronger the structure will be.
What’s in the kit? Be careful when selecting a polytunnel kit, always check what’s included in the price, and look out for those hidden extras.
Hoops When comparing polytunnels it’s wise to check how many pieces the hoops will be supplied in.
Polytunnel hoops can be supplied in 2, 3, 4 and even 5 pieces. When they are supplied in so many pieces this can weaken the framework and you may require extra supports, which will often be supplied at an extra cost. The less pieces the stronger the hoop and the easier it will be to construct.
Why straight sides Having a straight side on a polytunnel gives extra working space right up to the sides and reduces the risk of damage with tools etc.
Securing your polytunnel Anchor plates are commonly supplied with a domestic polytunnel that is being placed on soft ground; they can be secured in place with soil or for extra durability - concrete. Most allotments do not allow concrete to be used so it is always wise to check first.
Polythene Always select an anti condensation (often referred to as anti-drip) polythene to retain light clarity and protect your crops. Ideally fit the cover on a warm calm day. If fitted on a cold day you may need to re-tighten the polythene if it goes slack ensure your polytunnel has a facility to do this.
Anti hot spot tape Ask: Is Anti hot spot tape included? This tape creates a barrier between the framework and the polythene, thus preventing any heat build up from the steel to be transferred causing (possible) weakening to the polythene. It should be included as standard.
Doors There are several options available, hinged, sliding, timber, aluminum or if your good at DIY why not save some money and build, your own. Sliding doors are not prone to wind damage are safer. Aluminum doors are durable and wont warp or stick. Door that are supplied with top and bottom panels in allow you to have netting in the top section and polythene in the bottom. This will give a natural air flow when the doors are closed.
Base rails A base rail is put in place to avoid having to trench the polythene. The polythene will be secured to the base rail. Base rails are available in either timber or aluminum.
Side rails Side rails are installed when you require side ventilation; side ventilation is not normally required on polytunnels less than 30ft long. Side rails also offer an ideal opportunity to add a gutter system to collect rainwater.
Crop bars Are great for adding strength to the structure and ideal for supporting or hanging crops such as tomatoes or suspending hanging baskets. Crop bars can be added to your polytunnel for little expense.
Irrigation Regular watering in a polytunnel is a necessity and during the warmest months can be required daily. An irrigation kit can help with what can become a monotonous task and keep your plants watered while you’re away on your summer holiday.
Construction Choose a couple of warm days, a couple of friends and a good read of the instructions and it CAN be done without the help of a professional. However, if you feel you may need some help, most companies offer a construction service; speak to your supplier for more information.