Nick Hopwood
12 Jun 2019
10 people, a polytunnel canopy, and a windy day.
In June 2019, we began building our polyutnnel to create optimal growing conditions. The enhanced microclimate allows plants to be sown earlier, remain inside year-round with protection from the elements, and develop stronger root growth. It also provides a barrier against browsing animals such as rabbits and deer-although we have occasionally found the odd pheasant inside the tunnel.
We quickly realised that Wetley Moor Common is a notoriously windy place, as it is relatively open with no significant windbreak in the form of trees on the west side of the site. The prevailing wind moves west-to-east opposite to the east-to-west path of the sun in the UK.
Our polytunnel was positioned facing the west, as this was the most level ground on the site, close to a water source, and relatively remote. Any browsing animals would need to cross a large stretch of open ground to reach it, increasing the likelihood that they would be disturbed and scared away.
By June 2019, we had completed the frame of the polytunnel and were waiting for the right weather conditions to attempt the canopy. Eventually, we realised it was never going to be perfectly calm, so we chose a day that felt still enough to give it a go.
You don't truly appreciate how windy it is until you're trying to stretch an enormous canopy over a polytunnel frame. What felt like 3 gruelling hours (but was in reality closer to thirty minutes) involved a significant amount of stress, shouting (some cursing), and sweating before we finally secured the canopy in place and buried the edges into the ground.
To any installation professional reading this: I take my hat off to you - it is not easy!
Once installed, we were able to appreciate the benefits of a polytunnel, which include:
Extended growing season. Plants can be sown weeks before the soil outside is warm enough, and with insulation they will continue to grow without the restraint of frost and really cold weather.
Improved climate control. The tunnel protects from frost, wind, and heavy rain, has a warmer temperature than the outside, and reduces evaporation so less water stress for the plants.
Pest and Disease reduction. There is a physical barrier against birds, rabbits and insects. It reduces fungal diseases by avoiding direct rain splash on the foliage, and controlled entry allows you to introduce beneficial insects.
Cost and efficiency advantages. They are cheaper than greenhouses of the same size, relatively flexible even though ours is buried into the ground, and can double as a dry work area for potting and storage.