Many people plant marigolds (Calendula officinalis, not the French marigold, Tagetes) as a 'trap' crop, but the 'trap' attracts aphids, particularly blackfly.
The theory is, if the blackfly inhabit the marigolds, they won't inhabit your roses or whatever it is you're trying to protect.
In my experience, blackfly do love marigolds - not quite as much as they love nasturtiums, possibly - but there are so many of them, not only are the marigolds covered in blackfly, but
so are any surrounding plants they particularly like.
Doesn't stop me growing calendula anyway
- I love their cheerful colour and their repeat flowering habit (if you deadhead, that is).
As for Tagetes, the French marigold, this one is said to be a companion plant underneath tomatoes to keep whitefly away.
In general, there's very little scientific evidence for the idea of companion planting, but that doesn't mean some of the ideas don't work -
there just hasn't been much scientific testing going on.
Here's a link for more information https://www.sarahraven.com/articles/companion_planting_-_protect_with_plants.htm
gardening.stackexchange.com/users/1380/Bamboo
I haven't done specific research, but am happy to provide you with my personal experience.
Every year I grow many varieties of marigolds and they're always among the least bothered in my garden.
Animals who eat annuals and perennials planted alongside my marigolds almost always completely ignore them.
Those include chipmunks, rabbits, squirrels, and larger things like raccoons and opossums.
However, if I don't have any other flowers at all, the marigolds are somewhat vulnerable, but not in a fatal way.
Very rarely, if there's nothing else at all, one of my outdoor friends will bite the stem, leave the flower on the ground and not bother the root system.
The marigold basically looks like I've dead-headed it, and pretty soon it produces more flowers.
I've never found bugs of any kind on either the flowers or the leaves, even when they've decimated related species, such as dahlias, in the same garden.
I don't use pesticides, and am frequently willing to give up a plant if something living out there wants it that badly.
One of the reasons I grow so many marigolds is that I know I'll have a very long season and a lot of happy plants!
Here's a baby bunny resting under my marigold.
The hole to the left of its head is from a young snapdragon plant which had been uprooted by a chipmunk.
I know it was a chipmunk because I saw him do it!
gardening.stackexchange.com/users/7305/Sue Saddest Farewell TGO GL
Marigolds will keep some animals away - works best on insects.
Some people say marigolds will keep cats out of a bed, but I have had some feral cats that hadn't read this
and they went in the beds and did their thing where the marigolds were.
Marigolds will keep nematodes away from the members of the Solanacea family - tomatoes, peppers, petunias, tobacco, potatoes.. (For anyone who wants to get uppity about tobacco - I'm a Traditional Indn; we grow tobacco because it is Holy so you need not offend us by patronizing us about our use of it.
Thank you.)
Cheers!
gardening.stackexchange.com/users/14233/user223217
Oh cute...
Marigold plants are said to help keep predators/insects away
but I've never seen anything that would verify this
...grow marigolds for their beauty...
they are STINKY
so maybe that helps.
Grins, I've never seen that marigolds helps with; cutworms, aphids, slugs, earwigs, powdery mildew, or any regular problem for other ornamentals.
Vigilance, going out at night for instance to see what is going on...is the bestest pesticide ever.
Some very simple concoctions are worth their weight in gold.
Such as high pressure water stream.
Making
sure you keep the humidity down especially at night.
Milk (1:9 ratio) is incredible with powdery mildew, cats for mice (do not use poison), and I use Neem when truly challenged.
Great stuff.
But read the dang information closely!
Best to use preventative measures not the bandaids of pesticides.
Companion planting is cool but in all my years of education and experience never have I seen a difference.
Takes a broader and more educated understanding to make a difference.
Ventilation...lots of moving air, not so much moisture...takes pruning and adding more ventilation...going out at night to chop cutworms in half...
there would be only a few, slugs same thing only get them on the lawn, poor things, earwigs; get rid of their 'condominiums' and favored habitat...do not rely on Marigolds for any kind of protection.
gardening.stackexchange.com/users/3351/stormy
I seem to have fewer aphids on my runner beans when I plant marigolds nearby.
I try to plant the marigolds at the same time as the beans.
Planting marigolds after aphids appear does not get rid of them, in my experience.
I have not taken any 'scientific' measurements, this is just a subjective observation.
In about 30 years of growing beans, the 4 (approximately) with marigolds suffered less from blackfly.
gardening.stackexchange.com/users/14242/Peter Bill
Can this wonderful flower, when planted mature, keep away animals and bugs? I have read this on a few sites and want to know if it works. Is it true or even partly true? Has anybody done this themselves?
Can Marigold flowers keep animals away?
gardening.stackexchange.com
<flowers><pest-control><annuals>
gardening.stackexchange.com/questions/23905
gardening.stackexchange.com/users/14214/Ljk2000
Marigolds are supposed to keep insects away. The will keep nematodes away from the solanacea family. They work as a "trap" crop for aphids. Marigolds will keep  some  animals away and they work best on insects. Calendula officinalis attracts aphids, particularly blackfly, the theory being, if the blackfly inhabit the marigolds, they won't inhabit your roses or whatever it is you're trying to protect.  Marigolds are said to keep nematodes away from the members of the Solanacea family. Tagetes, the French marigold,  is said to be a good companion plant underneath tomatoes to keep whitefly away. Some people even say marigolds will keep cats out of a bed.
Marigolds will keep  some  animals away and they work best on insects. Calendula officinalis attracts aphids, particularly blackfly, the theory being, if the blackfly inhabit the marigolds, they won't inhabit your roses or whatever it is you're trying to protect.  Marigolds are said to keep nematodes away from the members of the Solanacea family. Tagetes, the French marigold,  is said to be a good companion plant underneath tomatoes to keep whitefly away. Some people even say marigolds will keep cats out of a bed.