Polytunnel Drip Irrigation PHDT Model farming Project Proposal

Polytunnel & Drip Irrigation PHDT Model farming Project Proposal Kegalle Region Eadella Estate /Orange Grove Division

What is a Polytunnel? • A metal framed semi-circular tunnel covered in hard wearing polythene with UV inhibitors to maximise its lifetime. (Nowadays can be up to 10 years) • Over 90% of light is transmitted through the polythene, and the light is diffused which prevents plants from shading one another. • • Inside a polytunnel it is possible to recreate a Mediterranean climate and therefore grow exotic fruits and vegetables in your own garden or just extending the growing season of traditional produce. A solar tunnel is a hybrid between a polytunnel and a greenhouse and is constructed with vertical sides a covered in a reinforced green polythene mesh.

Advantages • Cost - For the price of very small good quality greenhouse, it is possible to buy a polytunnel four or five times the size and therefore cultivate many more crops. • Flexibility - Not as permanent as greenhouses and therefore smaller models can quite easily be moved around. • • • Warmer - An enormous quantity of air is enclosed by a polytunnel and so it stays warm much longer than a greenhouse. Extended Growing Season - If bubble insulation is used it is possible to ensure a frost free winter and an even longer growing season. Easy - It is relatively simple to erect and very easy to maintain

Disadvantages • Aesthetics - A greenhouse is much more attractive than a giant tube of polythene. • Vulnerability - Vulnerable to playing children, excited cats, and stray lawnmowers / strimmers. Once you have torn the polythene of a polytunnel, no amount of taping and fixing will hold the damaged area together for long. • Ventilation - A polytunnel can be much more difficult to ventilate than a greenhouse, and so the levels of humidity inside can promote the proliferation of fungal diseases amongst your crops. • Shelter - Needs to be located in a sheltered spot out of the wind or you risk losing it. • Temperature - Polytunnels can become very hot in the Summer months. • Pests – As with greenhouses pests such as White Fly and Red Spider Mites can be troublesome.

Choosing a Polytunnel Four Golden Rules : 1. Make sure hoops are strong enough to withstand snow. Steel hoops, galvanized inside and out are ideal. The structure will also be stronger if the hoops are no more than 2. 4 m (8 ft) apart. 2. Choose a wide tunnel rather than a narrow one. A short wide tunnel is better than a long narrow one for working space and ventilation. 3. Choose the best available cover that you can afford. Make sure that is treated with an anti-fogging agent. This prevents annoying drips down the gardeners neck and (more importantly) harmful drips of water onto the plants. The extra cost spent will be more than paid for by longer life and greater energy efficiency of your tunnel. 4. Always use “Hot Spot” tape. This will protect the sheeting from the increase temperature of the steel hoops in the summer causing the polythene to become brittle and crack.

Polytunnel Essentials • Construction options : Trench or Ground Bars? Frame Polythene Cover Hotspot Tape Repair Tape

Siting and Services • • Have the ridge running East / West to get the best from the sun. Sheltering your polytunnel from the wind will make for a warmer polytunnel. Siting it between buildings may cause a wind tunnel. Avoid deep shade. Trees should not shade or overhang to reduce the risk of damage, but make good wind breaks when far enough away. • A level and raised site will avoid frost pockets and the risk of water logging in winter. • Some local authorities do require full planning permission for polytunnels. Check First!!! • A water supply is virtually essential for polytunnels of 50 m 2 • Electricity supply is useful for lighting and heating. Always use an RCD protected supply

Watering & Irrigation • Make sure you have easy access to water, your plants will grow surprisingly quickly and take up a lot of water. • Ideally use rain water. If not tap water can be used either directly from the tap of from a storage butt. • Use a few potassium permanganate crystals (just enough to lightly colour the water) to eliminate bacterial and fungal diseases and algae. • • Do not over water as polytunnels are susceptible to mould. Damping down (watering paths) will help to reduce the polytunnel temperature on very hot days. 1000 litre IBC’s can be purchased cheaply on e. Bay and provide the added advantage of providing a thermal storage facility. Are automatic irrigation systems worth the money?