Four o’clock flowers are beautiful and hard to remove

When I was in graduate school I lived in a hillside apartment that had beautiful four o’clock flowers in the front yard. They came in different colors, mostly bright pink to magenta, and they self-seeded themselves every year. I liked them. Hummingbirds liked them too. Even the large shiny black seeds were pretty.

Every afternoon the flowers would open, and the front yard went from green to colorful. Generally, four o’clocks (Mirabilis jalapa) grow better in full sun, but this area was partially shaded.

The soil wasn’t overly fertile in that spot. These plants grow best in deep fertile soil, but they thrived anyway. I never watered them either, and I remember 1983 was a very dry year in West Virginia. Four o’clocks usually have few disease and insect problems, which makes for low maintenance.

Plants grow two to four feet tall, so they can be pruned into a hedge for the growing season. Four o’clocks bloom throughout the summer and fall, and the flowers are quite fragrant. They die to the ground in winter.

Four o’clocks are in the nightshade family along with potato, tomato, peppers, eggplant and tobacco. This one is bred for its flowers. I wouldn’t recommend eating it.

When I moved to North Carolina I learned to dislike this plant. They became a true perennial and developed huge tubers that virtually engulfed whole flowerbeds. In all but the sandiest soils they were nearly impossible to remove.

If that weren’t enough, the large black seeds spread everywhere. I never noticed this before in northern areas. Perhaps that’s because I lived in town. Birds eat the seeds, so this can be quite an invasive plant in warm climates like ours.

This nightshade family member is one of the plants deer and rabbits normally avoid. When plants are damaged they usually recover quickly. Deer, dogs and other animals may not eat landscaping, but they still trample it.

Speaking of dogs, four o’clock tubers and seeds are highly toxic to them. Dogs, especially puppies often like to dig up and chew on the tubers. Alkaloids are the likely toxicity culprit. Symptoms range from vomiting, diarrhea, skin rash and redness around the mouth. When detected early it isn’t fatal.

Regardless, it’s not a good idea to treat it yourself. If you suspect four o’clock poisoning, the smartest option is to take your animal to your local vet.

Many broadleaf weed killers will kill four o’clocks. This is probably the way to go when they spread into lawns. Round-up will control it too, but you must be careful to hit only the targeted plants.

As far as four o’clock culture goes, they are great north of zone seven. In warmer climates some thought is required. Eventually they will take over an area, and that is fine if you like them. Another option is to plant them in pots.

Likely they won’t overwinter in pots around here, but it wouldn’t matter if they did. I still have a soft spot for them, but I prefer to plant them away from other things.

Four o’clock flowers and shiny black seeds

Sorry, I posted the wrong picture earlier. That one was evening primrose and I’ll post that column next week.

Ted Manzer teaches agriculture at Northeastern High School (

About tedmanzer

I grew up in Old Town Maine and got a B.S. at the University of Maine in Plant Sciences/ minor in Botany. From there I moved to West Virginia and earned a M.S. in Agronomy at WVU. I also met my wife there. She grew up in rural WV as the daughter of tenant farmers who raised cattle and hogs. Their lifestyle at times was one of subsistence and I learned a lot from them. I've always been a foraging buff, but combining my formal botanical knowledge with their practical 'Foxfire-type' background opened up my eyes a little more. I recently retired from teaching high school agriculture after 25 years teaching with my wife. Until recently I wrote a weekly nature/foraging column for the local paper ( I also have written several Christian nature/adventure novels that can be purchased on Amazon in Kindle format. One is a five book family saga I call the 'Forgotten Virtues' series. In the first book, Never Alone (presently out of print), a young boy comes of age after his father dies in a plane crash, and he has to make it alone. The second book, Strange Courage, takes Carl from his High School graduation to his recovery from a nasty divorce. The third book, Second Chances, takes Carl from his ex-wife's death and the custody of his son to his heroic death at age 59. The fourth book, Promises Kept, depicts how his grandchildren react and adjust to his death (this one is not yet published). In the final book, Grandfather's Way, his youngest and most timid granddaughter emerges from the shadow of her overachieving family and accomplishes more in four months than most do in a lifetime. I use many foraging references with a lot of the plants I profile in these articles in those books. I also wrote a romance novel titled Virginia. It is available on Amazon and is a different type of romance from a man's perspective.
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3 Responses to Four o’clock flowers are beautiful and hard to remove

  1. tonytomeo says:

    My colleagues dug up several of the big roots while they were still dormant, and were amusingly baffled by them. They had no idea what they were! The roots really were big! In the past, I tried to transplant the roots, thinking that the bigger, the better, but they do not recover from transplant very well. Big fat roots are no better than smaller roots. They grow so fast from seed that the roots are not needed anyway.

    • tedmanzer says:

      That’s been my experience. I usually don’t mess with those big things. I bet in your area you can’t get rid of them either. In cooler climates they aren’t a problem. They re-seed but don’t develop the big tubers.

      • tonytomeo says:

        Yes and no. For some reason, they do not spread as badly as one would think. I do not know if the seeds get eaten, or why they do not become more invasive. In the spots where they are established, they make MANY seedlings. However, if the big yam like roots get dug and disposed of, and the seedlings get kept down the following year, they are not that difficult to control. Like so many weeds, we keep them out of some spots, but allow them to stay in others.

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