1852, from German Kinder-Garten (1840), literally "children-garden, garden of children," a metaphoric name from Kinder "children" (plural of Kind "child;" see kin (n.)) + Garten "garden" (from suffixed form of PIE root *gher- (1) "to grasp, enclose"). Coined by German educator Friedrich Fröbel (1782-1852) in reference to his method of developing intelligence in young children. Compare the double sense in nursery
Kindergarten means a garden of children, and Froebel, the inventor of it, or rather, as he would prefer to express it, the discoverer of the method of Nature, meant to symbolize by the name the spirit and plan of treatment. How does the gardener treat his plants? He studies their individual natures, and puts them into such circumstances of soil and atmosphere as enable them to grow, flower, and bring forth fruit,-- also to renew their manifestation year after year. [Mann, Horace, and Elizabeth P. Peabody, "Moral Culture of Infancy and Kindergarten Guide," Boston, 1863]
The first in England was established 1850 by Johannes Ronge, German Catholic priest; in America, 1868, by Elizabeth Peabody of Boston, Mass. Taken into English untranslated, whereas other nations that borrowed the institution nativized the name (Danish börnehave, Modern Hebrew gan yeladim, literally "garden of children"). Sometimes partially Englished as kindergarden (a form attested by 1879).