We have grown so accustomed to sharing our houses with plants that it may be surprising to learn that it was only in the last century that plants began to move indoors. The story of how this came to pass is an engrossing and complex one, involving many separate strands: the horticultural explosion of the Victorian period, stimulated by the plant hunters of the golden age, changing styles of architecture, new techniques of heating and lighting, the cultural values implicit in home design and decoration, and the changing role of women. Tovah Martin weaves these strands together in a chronological account of the introduction of houseplants in America, starting with the first bulbs brought indoors for forcing, through the successive introductions of ever more exotic plant materials, including the proliferation of ferns. It is a story equally rich in plant lore and insights into American culture. Once Upon a Windowsill is one of those books that manage, through a perceptive examination of a seemingly “odd” topic, to shed surprising light on a much larger subject. This is an important and fascinating work of social history.