[jrumbut]

They also had a wild system for growing citrus fruit in trenches in the USSR.

https://solar.lowtechmagazine.com/2020/04/fruit-trenches-cul...

I've always wanted to try it in my own cold environment.

[HarHarVeryFunny]

I've seen Youtube videos of people growing citrus, among other things, in colder climates in "greenhouses" made of plastic sheeting heated by a thick layer of woodchips which slowly decompose and give off heat.