I've seen other manifestations of "vertical" farming both in my neighborhood and elsewhere. Of course stakes and trellises are ubiquitous, and in most cases urban farmers here arrange their crops in a fairly straightforward order of height, with the tallest climbers along the northern edge of the plot. Though tall plants might be better off in the center, to get sunlight from more sides, it's too likely that they will shade other crops that way. I've seen plots that take advantage of a light-colored wall to the north to reflect sunlight coming from the south back onto tomatoes and eggplants. It might be less than ideal, but I've learned that urban farming is full of compromises.
One of the more exciting recent urban farming trends is a happy coincidence between culinary evolution and environmental consciousness, and deeply rooted in tradition. The goya , known as "bitter melon" elsewhere, is a climber that has long been a part of Okinawan cuisine. It is an ideal crop to use as a "green curtain," in which leafy plants are trained to grow up a lightweight trellis, ropes, or net, in order to shade the exterior walls of a building and reduce energy consumption. Trellises like these were a common feature of traditional Japanese houses, which were most often engulfed in morning glories. The government in recent years has been encouraging the use of green curtains, and people have learned to love the bitter taste of goya (and its reputed health benefits). And because goya is a vertical crop, it is ideal for Japan's tiny garden plots. It's a true win-win situation.
Vertical thinking in Japanese urban farms is manifested in a variety of other ways as well. Hanging pots of herbs and other plants are common pretty much everywhere in the world, but here it can be the only way to find space to grow things. And a friend of mine who lives in a western suburb of Tokyo has worked around the serious spatial limits of his backyard—only about eight by 10 feet—by building a small vertical farm comprised of steep cinderblock terraces that forms the rear wall of his yard. Each step of the terrace is only about two feet wide, and rises about two feet higher than the one below it, to a total height of about eight feet. The brilliance of his solution is that each level gets full sunlight, while forming a microclimate appropriate for different crops: strawberries and root vegetables that like it cooler are planted below, lettuce in the middle, and tomatoes highest up. As an architectural feature, it also looks striking.
Lastly, Japanese farms have always included elements of wetlands, an essential feature of the natural landscape that provides habitat for many species, regulates water flow and absorption, and stabilizes the temperature and moisture content of the air. On farm plots, ponds serve similar purposes, and even ornamental Japanese ponds, home to carp, turtles, and frogs as well as the innumerable insects on which they feed (and attractive to birds as well), usually share these characteristics. Few urban farmers have space for ponds of any notable size, but they have discovered ways to bring the benefits of wetlands into tiny areas. The shadier corners of my friend's terraced yard are ideal for aquatic vegetables like kuwai ; grown in large, water-filled plastic buckets, it tastes like water chestnut but is unrelated. Even in this "unnatural" setting the water attracts wildlife and serves its environmental purpose, with the undeniable advantage of being moveable. I've seen lotus root grown in buckets—one plant per bucket because of the large size of the floating leaves. And I've come across all manner of troughs, ice chests, old aquariums, and even bathtubs being pressed into service here to grow aquatic plants in tight situations.
Techniques similar to some of these are already familiar outside of Japan, but it is eye-opening to see how they've been adapted to the hyper-constrained spatial conditions the country has long experienced, where almost every element must serve more than one purpose. And it's difficult to convey the uncanny way that people like my neighbors identify promising farmland among the chaos and jumble of the city. Significantly, although printed information about some aspects of these enterprises may be available, for the most part the knowledge is passed down orally, from person to person.
As we increasingly wonder how to integrate farms and other green spaces into our evolving urban fabrics, we would do well to examine these Japanese examples closely, to try to grasp their principles. But we should also try to discover how the human relationships that make them so successful, as well as the enthusiasm and pride of place that sustain them, are nurtured.