Foxfield Permaculture LAND Centre
Foxfield Permaculture LAND Centre

Self Watering Polytunnel

The ploytunnel was one of the first things we put up at Foxfield. I carefully selected the site so as to get year round sun, taking nearby trees and their full height shading into account, and where it would be largely protected from south westerly winds. It also had to be close enough to the poultry areas to make a benefical relationship possible - the duck pond is right on hand so I can utilise any nitrogen rich duck water if needed, and I can chuck old crops out of the tunnel directly to the chickens, squishy tomatoes they appreciate immensely!


Firstly I created a sheet mulch of card and compost (kindly donated by the previous owners mowing the field for years and emptying grass clippings and then leaving for me) and lawn mowings on top, planted potatoes through and this cleared the area of grass.


We put the polytunnel up around the bed so that by the time the potatoes were harvested we had a usable tunnel and cleared, nutrient rich soil inside.


We next created raised bedding using old paving slabs at the back of the beds, to raise the soil level above ground level and crazy wine bottle curvey bedding edging at the front. The wine bottles were sourced from local pubs, a classic unused resource, not waste!  They were 3/4 filled with water before being malletted in upside down, use a wooden board to protect them and wear safety glasses. These then act as little mini solar gain storage heaters (as do the paving slabs too) on cold frosty nights when they've soaked up the clear winter sunshine the day before. Being 3/4 full they do not fracture when really hard frosts do actually freeze the water, as full ones do. 


Next I laid several circuits of recycled rubber soaker hose at ground level before burying under repeated applications of compost over the years. Some of the oldest soaker hose is over a foot deep now and this means I can water the poly plants from below the soil surface, perfect for encouraging tomatoes to send roots deep and preventing too much water evaporation and  humidity causing blight etc. Tomatoes in particular will seriously wilt in hot weather if they have been repeatedly top watered making their roots grow out  at the top level where the soil is damp. The soakerhose can be connected to several water butts, 2 that collect rain from the poly roof itself (a second layer of plastic is batoned into 2 free standing gutters that feed the end butts, so when it rains outside it waters inside! Also I can connect to a 1000ltr tank that harvests all the rain from the house roof, or even to main hose if necessary. I have a zero effort watering system and a polytunnel that can effectively water itself.


I also encourage chick weed to grow in the poly - it is a shallow rooted ground cover that start up in the spring, copes with very dry mulches, is easily pulled up and used as a crop for the poultry who love it, can also be eaten in salads, and most of all provides another evaporation barrier to keep your soil moist beneath. It does not compete but will smother smaller plants if allowed to grow too tall so pull it up and leave it as a drying mulch and new seed will set very easily.

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© Alison Ensor