Humans can not live long without access to nature, and certainly not happily. In Japan rustic or highly refined large gardens were vital parts of temples, for contemplation, meditation, as a mental retreat... 
...in cities, private citizens who could afford it, built courtyard gardens, tsuboniwa, after its general size of one tsubo (about 3.3 square meters). Of course, if you had money, you built larger...
...but even if you lived in a grotty part of town surrounded by businesses or noisy industry, you would add something natural or organic to your tokonoma (alcove), even if only a single stem of a flower in a sooty old clay pot.
