Coffee has been traditionally grown within a forest containing both native flora as well as other productive species (cacao, banana, vanilla, etc.) that grow well under taller trees. So in a sense coffee _requires_ vertical farming, except that the vertical space is only occupied by coffee plants at one place. John Vandermeer of U. of Michigan has been studying coffee cultivation as a primary example of food forest, and has been pointing out the negative effects of full sun (and yes, full rain) intensive coffee cultivation on the resilience of the production system. I am surprised that the article does not mention these aspects of coffee.