South-facing walls are ideal spots for most fruit trees, especially the most tender ones such
as peaches. It is even possible to grow fruit trees and shrubs in containers if the site has no
soil. Morello cherries and some plums will grow against a north wall. These can be stacked
with currant bushes and alpine strawberries to give high production in a shady spot. Anoth-
er useful shade-tolerant perennial is the Jerusalem artichoke, and there are many others,
both annual and perennial. Shady spots can also be made significantly lighter with white-
painted walls, and even mirrors, to reflect light into them.
All our common vegetables and fruit can be grown in cities, and some of the less com-
mon ones if we make use of the many sources of waste heat to be found there. What pro-
portion of our total needs we can grow there remains to be seen, but it will certainly be far
more than most of us would imagine.
People whose potential growing space is limited to a high-rise balcony, a series of win-
dow boxes or a small back yard can still grow a useful part of their food. Obviously this
will not amount to much in terms of the family's bulk consumption, but it can be valuable
both in terms of food value and money saving.
The difference in food value between green vegetables which are eaten within minutes
of being picked, and shop-bought ones, which were picked days before, is enormous. So
vegetables that are grown very close to where they are eaten have a nutritional value out
of all proportion to their bulk. This is especially true of salad vegetables. A kind of lettuce
which makes particularly good use of limited space is the 'Salad Bowl' type, which you
pick individual leaves from rather than cutting the whole plant. If hearted lettuce is pre-
ferred, some of the miniature varieties of Cos lettuce will grow happily in a window box.
Many leafy salad vegetables can be grown on the cut-and-come-again method: seed is
sown broadcast and when the seedlings come up they are clipped and allowed to sprout
again. This can be repeated several times, and the repeated clippings add up to more yield
than you could obtain off the same area by growing plants in rows and cutting them only
once when they mature.