How To Kill Nightshade In The Garden

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Ask a Master Gardener: Dealing with deadly nightshade

Q: My mom says a plant growing in my yard is called deadly nightshade. It's got small purple flowers with yellow centers, and it seems to be a vine. What is the best way to get rid of it? And how dangerous is it? I'm worried that my kids will be ...

Written By: U of M Extension Master Gardeners in St. Louis County | 4:00 am, Jul. 22, 2017

Bittersweet nightshade is sometimes called "deadly nightshade," but it is only mildly toxic. Photo by Catherine Winter

A: The nightshade you describe (solanum dulcamara) is not actually very dangerous, but it is mildly toxic. The red berries that form after the flowers die are the most toxic part, especially when they're still green. They contain a substance called solanine, which can cause nausea, vomiting and diarrhea if eaten.

Solanum dulcamara is known by a number of common names, including deadly nightshade, bitter nightshade, bittersweet nightshade and climbing nightshade. To make matters more confusing, there is another plant also commonly called deadly nightshade that is quite poisonous, atropa belladonna. It has showy, fragrant, bell-shaped purple flowers, not the yellow-centered flowers you describe. Atropa belladonna has been introduced in some parts of North America, but not in Minnesota.

The plant you have is not nearly as poisonous, but it's still a good idea to get rid of it because it can spread and choke out the plants you'd rather have in your yard. Unfortunately, pulling it doesn't tend to be effective because the stems just break off and the roots survive to grow again. If you don't have too much of it, try digging it up. Watch for new growth and dig that as soon as you see it. You may be able to smother new growth by applying a thick layer of mulch, such as wood chips or shredded bark.

If you have a lot of nightshade, you may want to use an herbicide such as glyphosate. Follow the instructions on the bottle, and apply it carefully. Don't get it on any plants you want to keep.

Interestingly, solanum dulcamara is in the potato family. The solanine in the berries is the same mildly toxic substance that potatoes can develop when exposed to light. That's why it's best to store potatoes in the dark and avoiding eating them if light has made them turn green.

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