Excerpt
Foliage has an important role to play in garden design. I am not suggesting you garden sans flowers, merely that you give leaves the same kind of consideration. Leaves can function like a supporting cast, scarcely noticed for the stars of the performance, or they can work together with flowers in an ensemble production. We think of certain showy flowers as seasonal signifiers. The first daffodils and pussy willows are exciting reminders of spring, just as chrysanthemums are a sign of autumn (At least they used to be. Clever manipulation of day length and temperatures now make chrysanthemums a year-round affair, and tulips are getting there too). Pity. Foliage can be just as powerful an indicator of seasonal change — sometimes blatantly so, as when leaves turn bright colors in autumn, and sometimes in a quite subtle manner, as when the pink-flushed fuzzy white leaves of oaks unfold from winter's resting buds. Winter flowers, so popular in English gardening, are scarce to nonexistent in much of the United States. Evergreen foliage can provide a quiet contrast to gray or brown twigs and bark, and to white winter snow.
Traditional Japanese garden design relies very strongly on foliage. Gardens tend to be small, so there isn't space for short-lived flowers. Rather, a potted herbaceous perennial or bulb — a chrysanthemum in fall, a lily in summer — is brought on stage when in bloom and then discreetly retired from view. The technique is similar, albeit more intensive in magnitude, with the great English estates. Passing moments in the garden see flowering plants removed and understudy replacements brought from the wings to be planted out for the next act.
Japanese poetic traditions strongly associate plants (sometimes flowers, sometimes foliage) with the cycles of their seasons. Keeping in mind that the classical Japanese calendar has a lunar cycle, unlike the arbitrary months of the Gregorian calendar, it is interesting to note these associations. Tree buds (ko no me) signify midspring, early March to early April, while young green plants (wakamidori) allude to late spring, early April to early May. Bamboo autumn (take no aki) is another poetic reference to late spring, that time of year when the leaves of evergreen bamboo turn yellow. Sprouting grasses and forbs (shitamoe) and fiddlehead ferns (warabi) are also used to manifest early and midspring.