The species related to the black nightshade are widely distributed in various habitats throughout the world, from tropical to temperate regions and from sea level to altitudes exceeding 3500 m. Their wide tolerance of habitat types, their ability to flower while still young and their prolific seed production all contribute to the success of these species as widespread weeds.

They are generally found in disturbed habitats, such as roadsides, often on arable land especially the edges of cultivated fields and plantations, in hedgerows, on railway cuttings, quaysides and rubbish tips, in areas around buildings and houses, under trees, on forest and grassland margins, as garden weeds, on shingle beaches, riverbanks and in gullies in most parts of the world.

The species mainly colonize moist environments, only occurring in areas of low rainfall when the land is subject to irrigation. Indeed the intensification of agriculture, particularly when associated with the extension of irrigation systems has been largely responsible for the rapid spread of this species.