Gardening has been practiced by humans for food and aesthetic purposes for thousands of years. As urbanization intensifies globally, gardening is increasing in both popularity and extent in urban and suburban regions of the world, thus increasing its impact on the environments. Here we discuss the health benefits and risks of home-grown vegetables followed by an in-depth examination of how home and community gardening impacts the biological and physical environments of the world with a focus on North America. In addition to offering multiple health benefits, gardens may promote biodiversity by providing critical habitats for a variety of native plant and animal species. At the same time, gardening has the potential to alter cycles of carbon, nutrients and water in urban and suburban areas, consequently contributing to global environmental changes. Conversely, gardening may have a range of adverse impacts on the environment, for instance, higher nutrient runoff and increased risk of eutrophication in aquatic ecosystems. Intensive lawn care, particularly in North America because of its large lawn areas, could divert essential resources, such as manpower, fertilizers and water, away from more ecologically and economically important activities. Exotic plants commonly grown in home gardens could escape cultivation and become noxious in their non-native habitats as already demonstrated by an increasing number of ornamental species, such as Callery pear and non-native honeysuckle, in the USA. As the world becomes more and more urbanized, the increasingly popular gardening will have greater impact on the abiotic and biotic environments of the world.