Was skeptical about companion planting with marigolds, now I'm a believer after 2 seasons

I used to think companion planting was mostly garden myths, especially the whole marigold thing in vegetable beds. For 3 years I had terrible squash vine borers and aphid problems in my backyard plot in Orlando. Last spring I finally gave in and planted a border of French marigolds around my tomatoes and squash. The difference was CRAZY - I didn't see a single squash borer and my aphid numbers dropped by maybe 80 percent. Now I'm debating if it's the smell driving pests away or if the marigolds just bring in the right predator bugs. Has anyone else had a similar experience where they doubted companion planting and it totally proved them wrong?

2 comments

2 Comments

jessicajohnson1mo ago

Yeah actually I gotta jump in here about the nematode thing. That's one of those garden myths that got blown way out of proportion. Some studies showed certain marigold varieties like Tagetes patula can help with nematodes but it takes a LOT of them planted right on top of the problem area for at least a full season. A border around your beds isn't gonna do much for root nematodes. The above-ground pest reduction you saw is real though and it's mostly from the smell messing with pest insects' ability to find your plants, more than just bringing in predators. I'd still rotate varieties but don't count on marigolds fixing a nematode problem unless you're willing to sacrifice a whole bed to them.

juliahall1mo ago

Read a study a while back that said marigolds release a chemical from their roots that repels nematodes too, so it's probably a combo of both smells and attracting good bugs. I've heard some people claim the effect drops off after a few years once the pests adapt, but then others swear by rotating the types of marigolds you plant each season. Might be worth trying a different color or variety next year just to see if it keeps working as well. Either way, it's almost like nature figured out a system way before we did, you just gotta trust it sometimes.