This title includes a number of Open Access chapters. Urban horticulture, referring to the study and cultivation of the relationship between plants and the urban environment, is gaining more attention as the world rapidly urbanizes and cities expand. While plants have been grown in urban areas for millennia, it is now recognized that they not only provide food, ornament, and recreation, but also supply invaluable ecological services that help mitigate potentially negative impacts of urban ecosystems, and thus increase the livability of cities. This book provides background on key issues in this growing field.