Black nightshade
Solanum nigrum L.
Botanical family: Solanaceae
Solanum nigrum, a small, very common wild member of the nightshade family found on cultivated and disturbed soils. Oval leaves, small white star-shaped flowers with a cone of yellow anthers (like a tiny potato flower), then round berries turning from green to dull black. A plant worth knowing on sight, so you don't mistake it, and to read what it tells you about your soil.
Toxic plant: learn to spot it
A toxic plant. The foliage and especially the green (unripe) berries are rich in solanine; the black berries look like little blueberries and attract children. Do not pick it and do not eat it: learn to recognise it so you can remove it, and keep it out of reach of young children. If swallowed, call a poison control centre. (Some cultures do eat particular strains, fully ripe and cooked: this is neither your garden's nightshade nor a beginner's practice.)
Full sun to partial shade
Moist, rich, on cultivated and disturbed soils
Moderate, moist rich soils of cultivated ground
Annual
Role in permaculture
You don't plant it: its whole value is in understanding it. As a bio-indicator it points to a fairly rich, moist, nitrogen-supplied soil (an indicative reading, not a lab analysis). Above all, as a wild nightshade it can host the Colorado potato beetle and diseases near your potatoes, tomatoes and aubergines: better to pull it up beside vulnerable crops than to let it settle in.
Poor companions
Same family: shared diseases and pests
Nutritional & medicinal properties
For educational purposes. Not a substitute for medical advice. Effects depend on the form, the dose and personal context.
Precautions & contraindications
A toxic plant, not to be eaten: see the safety warning at the top of the page.
Family behaviour: Solanaceae
In general, Solanaceae are very hungry for nitrogen and prone to blight (Phytophthora infestans). They like heat, sun and a rich soil.
Understanding families means learning one rule per family rather than every pairing one by one. Learn more →
Species & varieties
The best-known species and varieties in France.
Species
Keep in mind
Being "toxic" and "edible" do not contradict each other here: the glycoalkaloid content varies with strain, stage (green berries ≫ ripe ones), cooking and origin, hence populations that eat selected, well-cooked forms without harm, and others where it poisons. For a gardening audience, we err on the side of caution. Long called a "non-host" of late blight, it is in fact a variable alternative host depending on the strain. Sources: InfoFlora (Landolt values); EPPO: Leptinotarsa decemlineata; Flier et al. 2003, Plant Pathology (DOI 10.1046/j.1365-3059.2003.00922.x); Toxiplante.fr.
A note on rigour: many companion pairings are gardening folklore; this note sums up what the sources say, where there are any.
Key takeaways
- • Prefers full sun to partial shade exposure.
- • Ideal soil: moist, rich, on cultivated and disturbed soils.
- • Keep away from: Potato.