Greenhouses allow for more environmental control in food production when chosen over cultivation in exposed land. When the grower has full control over the environmental conditions, unique possibilities may be explored: Cultivation of food which might not survive in exposed outdoor conditions, gaining a month or two by early maturation, also more importantly is the potential for maximised food production which may drastically help in reducing environmental strain caused by large-scale farming and food demand, (eg: deforestation, chemical inputs, fossil fuel demand etc).
A step by step guide to building a greenhouse (also called a polytunnel) is depicted below. All materials may be sourced using recycled or eco-friendly materials – also there is no ‘standard build’ – the design and attributes may be changed according to the particular needs and local climate conditions. In this case however, the build was constructed on a nice sunny day in beautiful Eire!
The site had a weedmat in place for a couple of weeks to deter any unwanted plants and their seeds from taking over. After that, the area was leveled and tilled twice..
..since the soil profile was deep enough, no concrete was necessary. 3/4m poles were driven into the ground and aluminum loops inserted into the poles to create a basic framework..
..1m wide x 30cm deep trenches were dug out alongside the entire perimeter, this will serve to further support the covering and entire structure towards the end (note the richness of the soil)..
..heat resistant insulation was attached to all the poles. This prevents the heat transfer from the metal poles onto the greenhouse cover (which runs the risk of deforming/damaging the said cover)..
..additional framework is added onto the basic one, namely horizontal bars for added support and the possibility to attach hanging baskets, as well as wooden framework (pressure treated Red Teal bars) for the apertures..
..doors with wooden framework and polyethylene covers set in place onto the frame. The picture is onto its side to highlight the fact that once again there is no standard – doors may be sliding, projecting, covered or uncovered with a bug screen. This all depends on the particular conditions desired – to know exactly what you need is the first step to shape the construction upon..
..the greenhouse cover (polyethylene in this case) is lined across the framework for setting up. Greenhouse covers may differ in strength, material and also the light wavelength type and frequency they allow to pass through – once again determined by growing requirements, the usual greenhouse cover material is usually clear polyethylene as in this case..
..the cover is stretched onto the structure, fixtures and a few final touches in place will give this result! On this area (40ft x 17ft) conventional outdoor growing will probably support up to a hundred plants, in greenhouse soil production this number may be raised to around 200 plants – and if high-tech (also eco-friendly) systems are in place (such as aquaponic multi levelled NFT), there is a good possibility to support a whopping 800-1000 plants with zero additions of artificial fertilisers and the bonus of rearing fish – yes, you may go fishing in your own polytunnel!
For more info on these systems, check out a brief overview by following this link which will open in a new tab. More developments on the systems mentioned will be posted in due course, you may subscribe using the below link to receive them..