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The Truth About Marigolds

Tomatoes and marigolds make happy companions?

I love the internet. I hate the internet. It is the ultimate research tool and the worst echo chamber of misinformation. I just got burned by forming an opinion about marigolds, of all things, after reading an entry on a garden blog that breathlessly extolled the virtues of these pretty flowers as being helpful in repelling insects. This garden blogger made the marigold seem like the perfect flower for a tomato garden.

So, Farmer J bought a flat of them and I put them in the middle of our tomato plants.

We took some photos and I was all set to write a blog entry about planting this miracle flower in our tomato plots. I thought it would take me a few minutes to write. A short, simple and useful bit of information for our readers.

Then, I started researching this miracle flower.

I’ve heard that marigolds repel mosquitoes, nematodes, slugs, rabbits and will cure diabetes. Ok, I’m kidding about diabetes. The other claims all have multiple sources. However, I have yet to find a credible shred of information that supports the marigold as being much more than pretty flower. In fact, one site even suggests that marigolds attract spider mites, which are an enemy of the tomato plant.

According to an article from the Alabama Cooperative Extension System dispelling marigold myths, “Although the sunny annuals have been used in this capacity [repelling insects] for many generations, little documentation exists showing marigolds actually repel insects. In fact, they may attract harmful pests damaging not only the marigolds but also your vegetables.

I turned to the Washington State University Clark County Extension site and found this nugget, “Some research shows marigolds have an effect on certain soil-dwelling nematode populations.”

However, you have to densely cover the ground with the flowers and let them grow for 2 months for them to have an effect, and you have to plant the right species.

They don’t mention anything about repelling insects.

The Kansas State University Research and Extension site pointed me to the Iowa State University Extension site (link) which claims that “research studies have concluded they aren’t effective in reducing insect damage on vegetable crops.” I want to see the research. I need some original documents. I’m afraid that I’m caught in an Extension Echo Chamber.

I’m still researching, and I will dig deeper into this pretty flower. Hopefully I’ll come across this ‘research’.

I’ll admit this … Farmer T, the journalist, was blinded by the beautiful writing, the certainity in which the unsourced information was presented, and the childhood memories of the Marigolds in my mother’s flowerbed. I’m sentimental.

I wanted to yank the flowers out, but Farmer J dissuaded me.

I’ll admit that . The marigold, for years and years, was about the only plant that I could identify. Farmer J hates marigolds. I loved them. I thought this was my chance to sneak them into the garden.

Damn the echo chamber.

Check your sources and then check their sources. As that great orator, George W. Bush, once said, “There’s an old saying in Tennessee — I know it’s in Texas, probably in Tennessee — that says, fool me once, shame on — shame on you. Fool me — you can’t get fooled again.”

This entry was posted on Thursday, June 10th, 2010 at 8:17 am. It is filed under Companion Plants, Garden Advice. You can follow any responses to this entry through the RSS 2.0 feed.