Marigolds are multi-function plants. That’s true. They are pretty, make a nice dye, some have medicinal uses, and some are delicious. But do they repel anything other than plant snobs? Not as much as we’ve been lead to believe.
Once upon a time, in a universe far, far away, I had a vegetable garden with no fence. I also had a rabbit warren in my backyard. Somehow the rabbits never bothered with my vegetable garden, until I stopped surrounding it with marigolds. I had assumed it was the marigolds that deterred them and reading up on the matter, others seemed to agree.
So, What’s Changed?
The scientific community has changed its tune about marigolds. I don’t always trust the scientific community because a lot of them have no “in garden” experience and it is very hard to duplicate circumstances year to year in a single garden, let alone come to some type of consensus for all gardens. But with marigolds, I think I agree with them.
Forget about repelling rabbits. Researchers at Iowa State University and Texas A&M University even reported rabbits eating marigolds. I now suspect that my initial success was probably due to the quantity of marigolds I had planted, their strong scent, and the easy availability of clover throughout the lawn. My rabbits didn’t have to move to find food. They could nap, sun, and snack without effort.
What About Repelling Insects?
So if marigolds don’t deter rabbits, do they at least deter insect pests? Not so much. The population of bean beetles fluctuates with or without marigolds. On the other hand, aphids and spider mites are attracted to marigolds.
And don’t forget that all plants compete for water and nutrients. Planting a lot of marigolds in your vegetable garden can diminish resources meant for your veggies.
They Must be Good for Something.
What marigolds are good for is controlling nematodes. Sometimes. There are some species of marigolds, like the French Dwarf, that exude a chemical from their roots that is toxic to some types of nematodes. Arizona Extension1 suggests the following varieties: Bolero, Bonita Mixed, Goldie, Gypsy Sunshine, Petite, Petite Harmony, Petite Gold, Scarlet Sophie, Single Gold, and Tangerine.
Even then, the marigolds need to be in place for 3 – 4 months and then plowed under, before they really take effect. Arizona Extension suggests planting half your garden with marigolds and then flipping and planting the other half with them the following year. And that still only works if your nematodes are one of the species affected. However the marigolds don’t attract nematodes, so any that are in a part of the garden without marigolds will not be killed.
That’s a lot of marigolds. At least you can save the seeds from your plants and then save a few bucks by not having to buy more next year.
But don’t compost your marigolds just yet. They still do a nice job of attracting beneficial insects, like ladybugs and parasitic wasps, and they provide a decent source of nectar.
[For the record, I have since put up “rabbit fencing” a type of fence that has smaller openings on the bottom and larger openings toward the top. I also buried hardware cloth a foot or two below the ground, all around the garden. I had to add a floppy topping of chicken wire, to deter groundhogs, but that’s another story.
Blood meal and bone meal have had a slight deterrent effect on the rabbits, but they wise up pretty quickly and the blood and bone meal washes off just about as fast.]