2013 Garden Experiment-Companion Planting of Marigolds and Tomatoes

Each year I like to try some kind of experiment in the garden.  I truly believe that the best way to become a better gardener is to try new things.  This year I will be putting one of the most commonly talked about organic pest control methods to the test.  I am going to try a companion planting of tomatoes and marigolds to keep the stink bugs away.

One of my "porch grown" marigolds is about ready to bloom

One of my “porch grown” marigolds is about ready to bloom

If you believe everything you read, then you no doubt believe that marigolds are miracle plants.  It is truly amazing to me how many articles/posts there are on the internet making incredible claims about their bug fighting abilities. One of the more recent things I read swears that all you have to do is plant a marigold in each corner of your garden and all of your bug problems are solved.  While there may be some truth to the marigold’s bug fighting abilities, I really don’t believe they are going to very successful at riding my tomatoes of their stink bugs.

The above marigold two days after opening

The above marigold two days after opening

Now don’t get me wrong.  I really want my experiment to work.  In fact, I have gone out of my way to give the marigolds as much of a chance as possible.  Instead of trying to plant four plants in the corners of my garden, I am going to completely surround the tomatoes in marigolds.  For this experiment, I grew about 100 marigold plants from seed in my new back porch seed starting rack.  Once the little plants got up to about four inches tall I used them to line the triangular beds of my potager.  I planted the starts six inches in from edge and spaced them at six inches.  It took about 20 plants to line each bed.

My first "bug fighting" marigold of the year

My first “bug fighting” marigold of the year

Once the flowers were in, I planted the tomatoes.  For this experiment I am using romas.  Romas grow on nice, neat determinate bushes.  My thought is, those nice, compact determinate bushes will give all of those pesky bugs fewer places to hide.  I am also hoping that their relatively open form will allow whatever magic bug fighting qualities the marigolds possess to waft freely deep into the bush where the bugs are hiding.

Holidays mean free labor.  My daughter jessie helps me plant the marigolds for my experiment on Easter Sunday

Holidays mean free labor. My daughter jessie helps me plant the marigolds for my experiment on Easter Sunday

I apologize a little about my attitude here.  I really, really, really want the marigolds to run all of the bugs off.  However, I am very skeptical.  Even though I am doubtful of the marigold’s bug fighting abilities, I do truly expect they will keep any nematode issues at bay.  It is a proven, scientific fact that marigold roots secrete alpha-terthienyl.  This compound has insecticidal, nematodial and anti-viral properties.  It also stops nematode eggs from hatching.

I love my larkspur.  This has absolutely nothing to do with the experiment but it is lovely and i just wanted to include it!

I love my larkspur. This has absolutely nothing to do with the experiment but it is lovely and i just wanted to include it!

My last big garden experiment was growing potatoes in a box.  That one was a complete failure.  I had very high hopes for that one when the experiment started.  For this one, my expectations are a bit lower.  I expect to have almost aero nematode problems but I really don’t expect the marigolds to be very successful at keeping the bugs away.  Only time will tell.  Check back at the end of the season to see how it goes.

11 thoughts on “2013 Garden Experiment-Companion Planting of Marigolds and Tomatoes

  1. We planted marigolds around our tomatoes this year also! Also very skeptical, but hey, worth the try. We’ll see what happens. Love the larksput!

  2. Bob, My information is that French marigolds (with the small heads) are the effective ones. I planted mine a couple of weeks ago and I encircled each of my two big tomato plants with the flowers. I hope it works! Willeva W.

  3. I have always used marigolds with my tomatoes yes just because I read that its a great companion plant. lol I didnt check it out myself “) It will be interesting to see how your experiment comes out.

    • I have recieved lots of tips on type of marigold to grow, when to plant, spacing, etc. So. like you say, it is going to be interesting

    • I saw the Junk Gypsies on TV today and they were in your booth. Your sign was appropriately visible. Congrats! That is really very cool.

  4. Pingback: Fall Garden Experiment – Growing Sweet Potatoes in Containers | The Masters of Horticulture

    • It was kind of a mixed bag. Early in the season, the tomatoes that had the marigolds around them had noticeably fewer bugs that the tomatoes with no marigolds. However, as the season wore on, even the ones with marigolds got a lot of bugs. So, I was not sure how to call it. Early on, it appeared to have some effect but by the end of the season I don’t think it was making much of a difference. Thanks for the question!

  5. Jay,
    Would u plant marigolds next to your tomatoes next time u plant them?Maybe one should remove them towards the end of the season? , DUE TO YOUR STATED RESULTS ABOVE.Read basil planted next to tomatoes improves their growth and flavor.Also helpful in repelling thrips and said to repeal flies and mosquitoes.Told not to plant near rue or sage.
    Have u tried any other types of companion planting?

    • This is the only companion planting I have tried. While I liked the way the marigolds looked around the tomatoes I really don’t think they made enough of a difference for me to recommend it as a pest control method. I have also heard about planting basil near tomatoes. I can see where the smell of the basil might deter certain bugs, I am doubtful that the basil will change the taste of the tomato. While I think these companion planting combinations might reduce populations of certain insects, I don’t think they are extremely effective.

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