The Native American Three Sisters technique traditionally uses corn, beans, and squash as companion plants. The corn provides a trellis for the beans, the beans fix nitrogen for the corn, and the squash creates a cover layer on the ground to retain moisture (kinda like a living mulch).

I'm not that interested in growing corn, so instead I'm considering sunflower. I'm not sure, however, if corn traditionally interacts with the soil nutrients in the companion relationship in some important way that sunflowers wouldn't replicate. Could sunflowers make a good companion plant in a Three Sisters plot?

  • Would you build some kind of grow-frame yourself, and eliminate the corn? Essentially reducing it to Two Sisters? Or grow the corn anyway and give it away.
    – Criggie
    Apr 5, 2023 at 1:31
  • @Criggie not sure I fully understand your question, but my question is suggesting to have beans + squash + sunflower instead of beans + squash + corn. Let me know if this doesn't clarify.
    – Drake P
    Apr 5, 2023 at 5:58
  • the clarification was about building a physical frame to replace the supporting function of the corn. A literal trellis of wood or wire for the beans to grow up. By not having the corn you'd have two types of plants as companions, not three.
    – Criggie
    Apr 5, 2023 at 11:02
  • The original plan was to have a living trellis via sunflower, but given Rohit Gupta's answer, a wooden trellis might be a better idea.
    – Drake P
    Apr 5, 2023 at 18:51

1 Answer 1


Firstly I don't think the sunflowers will provide the trellis. I think they are much weaker than corn.

Secondly, I haven't heard of anyone using sunflowers for companion planting. Maybe because they slow down the growth of other plants.

Sunflowers can kill. Of all the issues with sunflowers, perhaps the most interesting and dire is their tendency to repress the growth of other plants. This is because sunflowers are allelopathic – they exude toxins that stop nearby plants from growing. Have you ever noticed that the grass doesn’t grow underneath bird feeders? That’s why. It’s good from the sunflower’s point of view, since it leaves a wide open space every spring for new seedlings to grow. But it’s bad for gardeners who want to grow lots of different plants in close quarters. Most plants are affected at least somewhat, but pole beans and potatoes are especially susceptible and should not be planted anywhere near sunflowers.


They can blow over. Another of the negatives of growing sunflowers is their shape. Sunflowers tend to be tall, with big leaves and flower heads, perfect for catching the wind. A big storm can take one right out, and there’s a good chance it’ll take out the plants around it too.

Read more at Gardening Know How: Sunflower Planting Pros And Cons https://blog.gardeningknowhow.com/gardening-pros-cons/sunflower-planting-pros-and-cons/

  • +1 for educating me on sunflowers. I did not know about their allelopathic nature.
    – Boba Fit
    Apr 5, 2023 at 16:07

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