Bush Beans and Marigold
Antagonist Pair — Keep Apart
The claim outpaces the evidence available for it - marigold's water and nutrient draw during heavy bloom is plausible, but nothing we located isolates a measurable competitive effect on bush beans specifically, as opposed to any other flowering annual sharing the same soil.
Mechanism: Nutrient Competition
Unlike its trap-cropping role elsewhere on this site, the traditional concern here is that marigold, particularly vigorous, heavily-blooming varieties, competes with bush beans for water and soil nutrients during its own extended flowering period, potentially reducing bean vigor in tightly shared soil.
Marigold's reputation on this site is overwhelmingly positive, which makes this pairing worth flagging as the exception rather than assuming the usual trap-cropping benefit applies here too.
A Different Marigold Story Than Usual
The concern here has nothing to do with pest control - it's about a heavily-blooming marigold plant drawing on the same limited water and nutrients bush beans need in shared soil. This is a generic resource-competition claim rather than anything specific to the chemistry between these two crops, and it hasn't been isolated in a trial we found.
If you want marigold's other documented benefits nearby, consider siting it with a different crop on this site where its trap-cropping role is better supported, rather than directly alongside bush beans.
Spacing
If growing both, give marigold at least 12 inches from bush beans rather than the closer 8-10 inch spacing used for marigold's more cooperative pairings on this site.
Watch For
This is one of the few places marigold shows up as a caution rather than a helper - don't assume marigold is automatically a safe addition to every bed just because it plays a beneficial role elsewhere on this site.
Frequently Asked Questions
Does a young, newly transplanted marigold pose the same risk as an established, heavily-blooming one?
Less so, at least early on. A freshly transplanted marigold hasn't reached the dense, water-hungry bloom stage this caution is actually about, so it isn't pulling hard on shared resources yet. Watch for the risk to build gradually as the plant fills out and starts flowering heavily, not from the day it goes in the ground.
I already have marigold growing tight against my bush beans - is it worth moving one of them now?
Probably not. Moving an established plant risks more immediate, certain transplant shock to either the beans or the marigold than the unconfirmed competition claim this caution is based on. If the beans look otherwise healthy, it's reasonable to just watch for stress through the rest of the season rather than disturbing roots to fix something that's still unproven.