And she elaborates on the use of snow scenes: "White powder is sometimes used for a snow scene, as snow-capped Fujiyama, the sacred mountain of Japan, is a favorite scene to carry out in a Japanese landscape garden – large or small. "
Also available online is a 1920 article from American Forestry, which asserts that the origin of the dish garden was as a model for landscape architects: "For several centuries the leading landscape gardeners of Japan have made miniature models of their work so their customers might see how the proposed gardens would look; very much in the same way an American architect will make a prospective drawing of a house, except in this case the garden is made perfect in every detail, except that it is in miniature. "
"For a number of years an annual contest or exhibit of these toy gardens has been held in the city of Kioto, at which the leading landscape gardeners of Japan exhibit their work. A great demand has grown up among the tourists who visit the land of the cherry blossom for copies of these miniature gardens to take back with them to America. In response to this growing trade demand, one of the large Japanese nurseries has opened a branch near New York City, where one of their expert garden designers devotes his entire time in constructing miniature gardens for the American public."
Thus the New York Times article; for those who couldn't afford the purchase! The grainy pictures included with the American Forestry article (below) may be examples from such a Japanese nursery of miniatures.
(more info in an 1892 article in the Atlantic Monthly, courtesy of Google Books)