It will take some time but my prediction is that sub-irrigated raised beds (wicking beds for you Aussies) will become the biggest thing in urban (and suburban) agriculture. The market is simply huge.
Doubling productivity, saving 80-90% of the water, avoiding contaminated city soil and being certified organic from day one is simply too hard to resist once people learn how to do it.
Growing Greens in Small Spaces
One of the ways for retirees to cope with reduced income and an empty nest is to downsize. My family grew up on many acres of land devoted to orchards and my grandfather and father always allotted an acre or so to growing our own food, as well. So when my folks retired, they “sold the farm” and moved into a modular home. Not only was their house now much smaller; their land was also drastically reduced. In spite of that, my dad commenced to garden in the space available.
He now harvests fresh vegetables or greens almost every day of the year in a plot of land measuring a mere 18 feet by 22 feet. When he moved in, it was covered with plastic mulch and topped with large pea gravel: a pretty desolate place. He raked back the gravel, cut through the plastic and dug down to create several raised beds for vegetables and flowers, and even planted four dwarf citrus trees. In between these larger areas, he set up five EarthBoxes (earthbox.com)—a self-contained gardening system—that he had already found productive and efficient for selected vegetables.