lowtechmagazine.com

M70ma TIL of "gas bag" vehicles developed during the gasoline shortages of the World Wars. They used 'town gas', a by-product of the process of turning coal into cokes.
R7ey8 TIL that Russia, using earthworks and cultivation techniques (and with little glass), pioneered growing citrus trees, known for incredible frost sensitivity, in temperatures down to -30C / -22F. Annual national production of citrus reached almost half a billion pounds in 1950.
KOBD9 TIL of "fruit walls". Used before greenhouses, fruit walls stored the heat from the sun and released it at night which created a microclimate that could increase the surrounding temperature by more than 10°C (18°F).