Planting gardens to support insect pollinators.

Global insect pollinator declines have prompted habitat restoration efforts, including pollinator-friendly gardening. Gardens can provide nectar and pollen for adult insects and offer reproductive resources, such as nesting sites and caterpillar host plants. We conducted a review and meta-analysis to examine how decisions made by gardeners on plant selection and garden maintenance influence pollinator survival, abundance, and diversity. We also considered characteristics of surrounding landscapes and the impacts of pollinator natural enemies. Our results indicated that pollinators responded positively to high plant species diversity, woody vegetation, garden size, and sun exposure and negatively to the separation of garden habitats from natural sites. Within-garden features more strongly influenced pollinators than surrounding landscape factors. Growing interest in gardening for pollinators highlights the need to better understand how gardens contribute to pollinator conservation and how some garden characteristics can enhance the attractiveness and usefulness of gardens to pollinators. Further studies examining pollinator reproduction, resource acquisition, and natural enemies in gardens and comparing gardens with other restoration efforts and to natural habitats are needed to increase the value of human-made habitats for pollinators.