Marigolds as Vegetable Companion Plants

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Marigolds are not just pretty in flower beds, they have a job in the vegetable garden as beneficial companion plants. No, that doesn’t mean they make good company and keep the veggies company. They can help lessen the damage done to vegetables by certain pests.

I’ve planted marigolds around my tomatoes for over a decade now, out of habit or tradition, I’m not sure which. I had heard long ago that marigold exuded a chemical from their roots that deterred soil nematodes. A quick Google search says this could be one of those unresearched facts that only experienced gardeners can speak to. Well, I consider myself the latter: My tomatoes always did well with marigolds nearby and have faltered without them at times.

Deterring Pests 

Members of a new online gardening group I just joined had their own opinions about the efficacy of marigolds as companion plants. I had posted a photo of my insect barrier protecting radishes from flea beetles, and one member weighed in with the idea of planting marigolds as a companion plant to deter the beetles. She said that planting marigolds in the area would also keep flea beetles away, which I hadn’t heard. A week later I noticed my garden neighbor had just planted marigolds around her sown crop of arugula, another flea beetle favorite. As you can see in the accompanying photo, it looks like she planted them just in time, too. Flea beetles had had a feast when the seedlings just emerged.

The academic community is uncertain if marigolds control pests other than root knot nematodes. Researchers at Rutgers University explored the effectiveness of marigolds controlling pests. They concluded that marigolds failed to repel cabbage, carrot and onion pests. I found an interesting article on the subject titled, “Magical Repelling Powers of Marigolds — Myth or Fact?

On the contrarian side of the argument, Newcastle University (UK), found in a 2019 study that marigolds significantly reduced the presence of white flies when used as a companion with tomatoes. The article is titled, “The Scientific Evidence That Marigolds Repel Tomato Pests“.

The literature on companion planting is rich. While not vegetable gardening per se, a website called “Lawn Starter” provides information on the use of edible plants such as blueberries and basil to help in keeping lawns healthy.

The only way to truly find out if marigolds can help in your garden and landscape is to plant some. As for myself, that’s exactly what I intend to do!

Meet Ellen Wells

When you’re raised on a farm, you can’t help but know a thing or two about gardening. Ellen Wells is our expert on edible gardening.…

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