Evidence has been slowly accumulating that the urban home gardens of immigrants or transnational migrants in the USA conserve food plant diversity with roots in the developing world. Published species lists for home gardens indicate that, at least at the species level, this diversity is not novel but consists of widely grown, culturally important plant species that are also available through the horticultural trade. In 2018, we returned to the home garden of a Mexican-origin household in Chicago and confirmed the identity of a plant provisionally identified as Jaltomata darcyana during an earlier inventory of the garden. A recently named species of Central America, J. darcyana has not been previously recorded in cultivation. Collection of this species from a Chicago garden suggests that urban gardens may harbor other novel species awaiting documentation by urban ecologists and botanists.

In the United States, interest in urban farms and community gardens is flourishing, yet the urban home food garden (UHFG) and its contributions to urban systems have been overlooked and understudied. To begin to address this gap, we are conducting a mixed methods study of African American, Chinese-origin and Mexican-origin households with home gardens in Chicago, IL. Study methods include in-depth interviews, participant observation, ethnobotanical surveys and analysis of the chemical and physical properties of garden soils. As of this writing, findings indicate that home gardening has an array of beneficial effects, contributing to household food budgets and community food systems, the reproduction of cultural identity and urban biodiversity. The majority of informants in the study were internal or international migrants. For these individuals, gardening, culture-specific food plant assemblages and the foodways they support represent a continuation of cultural practices and traditional agroecological knowledge associated with their place of origin. The gardens of some migrant households also harbor urban agrobiodiversity with roots in the Global South. At the same time, gardens may have less salubrious effects on urban systems and populations. A lack of knowledge of safe gardening practices may expose vulnerable populations to environmental hazards such as soil contaminants. Gardeners in this study reported using synthetic chemical fertilizers and pesticides, sometimes indiscriminately, and the repeated application of synthetic fertilizers and compost may contribute to the nutrient loading of urban stormwater runoff. These effects may be moderated by the relatively low bulk density and high porosity of garden soils due to tillage and the application of organic matter, which can be expected to enhance stormwater infiltration. While the UHFG's potential contributions to urban systems are significant, outreach and research are needed to help gardeners grow food safely and sustainably in ways that contribute to overall ecosystem health.

The purpose of this study is to identify key home garden species in order to address basic research questions aimed at understanding farmers' home gardens management practices. The study was conducted in two contrasting Hill and Tarai sites in Nepal with households (HHs) ranging from 355 to 634. Unlike larger production systems, home gardens harbour many species in small areas often with a few crop varieties and species that are not well represented in larger fields. Given the number of species and their small population sizes, species and genetic diversity are best studied by identifying representative key species characterizing the complex productive niches within farms. Although species diversity within community is large (172–342), 24 key species were identified for the study. There is no fixed size of a home garden. The log of home garden size and species richness was positively correlated (r = 0.42, P < 0.001). Species richness was significantly higher in vegetable followed by fodder, fruits and spices. This paper also explores the diversity in home gardens to identify the composition and characteristics of the key species and how they are managed, used and conserved. Most of the farmers save the seeds of these home garden species for their own use, but many also exchange and buy and sell seed in local weekly market. Farmers' practices for selecting seed vary according to the reproductive biology of the key home garden species. Home gardens provide the HH with fresh and diverse supply of nutritious food, which improves their self-sufficiency, while conserving diversity on-farm. Despite this, they are neglected in research and development by policy makers and researchers.