In The Hunt For Gardening Perfection People Ask Do Walipini: Underground Greenhouses, Work in UK? The Idea Is Attractive But Do Walipini Work In Our Colder Northern Climate?
Walipini is word taken from the Aymaran language of Bolivia. Or so it says on Wikipedia. And that it is a earth sheltered cold frame, is just about all it says that I rate as being very useful.
A search for photos of walipini on Google brings up plenty of photos about how to build a walipini plus the one I include here. This one seems to get recycled on social media countless times each year, which makes me realise there aren’t many photos of walapini in circulation. I’ll say more about wha the photo tells me later in this article.
What Are Walipini?
Simply described it is an earth sheltered cold frame. But from the photo it is easy to see it is. bit more complex than that. It is a hole in the ground that is around 2 metres (6 foot) deep. It usually has a transparent roof that is meant to be designed to get the maximum sunlight and hence warm the structure. The covering is also meant to retain heat.
Do Walipini Work?
In Bolivia, situated between 16-22 degrees of the equator, quite likely.
But will it work in northern climes where we are at longitude 50-60 degrees north? Well that is entirely different. The seasonal differences in the angle of the sun are extreme at these altitudes.
There is another issue.
Hot air rises and cold air runs to the lower points. So the bottom of a hole in the ground is always going to be much cooler than soil level. And though if we go deep enough the temperature in a mine or cave stabilises without getting anywhere near to freezing, in a hole in the ground it can go down to freezing very quickly in winter. As well it can in early spring and later autumn.
Then there’s the light issue.
Look at the image. It is all of shadow. We know plants need plenty of sunlight to photosynthesise (the clues in the name) but here we have growing space with less than optimal sunlight. Look at the vegetation in the photo. It isn’t exactly lush.
In case you want a few facts about this, in mid December the maximum angle of the sun where I live is 15 degrees. It barely comes above the horizon with some of our hills. In mid summer it reaches around 60 degrees.
In Bolivia, being closer the equator the sun is higher in the sky all year.
NB I’d be grateful for any expert that can furnish all the figures for this to contact me … Google isn’t as forthcoming as it might be!
As for the cover. If it is plastic it will break the wind but it doesn’t have much in the way of insulation qualities. If plastic could insulate it would be used to build houses and we wouldn’t need really thick slabs of polystyrene!
Do walipini work in northern climes? The physics are against it being a highly successful technique. Light levels, temperature etc are really against it.
Walipini In Victorian Britain?
Wikipedia suggests that the walipini design is similar in concept to the pineapple pits used by Victorian gardeners.
A pineapple pit was a shallow trench bordered by two walls, used to retain tons (yes, many tons) of decomposing horse manure that gave off a lot of heat. The heat passed through small gaps at the bottom of the wall and warmed the growing area and soil.
The whole growing area was covered in a greenhouse that was also often heated with additional water pipes.
It is nothing like a walipini.
The pineapple pit consisted of three trenches covered with glass, slightly below ground level, connected with two cavity walls. The outer troughs were kept filled with 15 tonnes of fresh horse manure, which gave off heat as it decomposed. This heat passed through small gaps at the bottom of the wall, rose up, and was then forced through gaps at the top of the wall, into the central trough. The central trough is where the pineapples were grown, at an artificially high temperature, due to the manure.
Is There Evidence Walipni Work?
“There’s not a lot of scientific research or peer-reviewed research,”Neil Mattson, professor and greenhouse extension specialist at Cornell University’s School of Integrative Plant Science
Conclusions: I’d love to think walipini work in the UK but I’m yet to see any evidence that they do or can.
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