How to get rid of a plant which is overtaking with its seeds?

[KarenMay]

This plant is becoming a menace!! I think it is called cigar plant but maybe not??? It has tubular root system and drops black berries/seeds? everywhere, even starting to reseed in the lawn. Nice for a but of hot pink colour but I'm over it!!  Can someone help me with a solution please 🌸

 

[EricL]

Hello @KarenMay 

The plant in your photo is not a cigar plant (which is typically Cuphea ignea)—it's actually Mirabilis jalapa, commonly known as the Four O’Clock plant or Marvel of Peru. It gets its name because the flowers usually open in the late afternoon. While its vivid pink blooms can be attractive, it’s known for being invasive in many areas, especially in warm climates. The plant develops a thick, tuberous root system and readily self-seeds through its black, peppercorn-like seeds, which explains the spread into your lawn. 

To control it, dig out the entire plant, ensuring you remove as much of the root system as possible—any leftover root pieces can regenerate. Avoid composting the seeds or tubers, as they might survive and spread. If it's coming up in your lawn, regular mowing before it flowers can help stop seed formation. Persistence is key, and over time, you'll weaken its spread. 

Is there a chemical spray you can use to control it?

Yes, you can use a non-selective herbicide like glyphosate (e.g. Yates Zero or Roundup) to control Mirabilis jalapa, but it needs to be applied carefully because it will kill any plant it touches, including lawn grass. For isolated clumps, cut the plant back and immediately apply glyphosate directly to the fresh regrowth or leaves when they're actively growing—preferably in warm, dry weather for best absorption. 

Be aware, though, that because this plant has a tuberous root system, one treatment may not be enough. Multiple applications may be needed to exhaust the tuber’s energy reserves completely. For lawn areas, spot-treat using a shield or Yates Zero Weeding Herbicide Applicator Brush to avoid harming the surrounding grass. Always read the label for safety and local usage guidelines.

Please remember to wear personal protection such as gloves, goggles and a mask when using chemicals in your garden.

If you need further assistance, please let us know.

Eric