Fruit Walls: Urban Farming in the 1600s

greenhouses,  we don't need no stinkin' greenhouses....

http://www.lowtechmagazine.com/2015/12/fruit-walls-urban-farming.html

Fruit Walls: Urban Farming in the 1600s

We are being told to eat local and seasonal food, either because other crops have been tranported over long distances, or because they are grown in energy-intensive greenhouses. But it wasn't always like that. From the sixteenth to the twentieth century, urban farmers grew Mediterranean fruits and vegetables as far north as England and the Netherlands, using only renewable energy.

These crops were grown surrounded by massive "fruit walls", which stored the heat from the sun and released it at night, creating a microclimate that could increase the temperature by more than 10°C (18°F). Later, greenhouses built against the fruit walls further improved yields from solar energy alone.

It was only at the very end of the nineteenth century that the greenhouse turned into a fully glazed and artificially heated building where heat is lost almost instantaneously -- the complete opposite of the technology it evolved from.  

I love this article. I came across this information years ago, and am hoping to use a fruit wall for some citrus in southern Oregon.