Combative planting?

[Ruderunner]

So the idea of companion planting is pretty well known, such and such plants grow well with such and such plants. Theres charts available to help determine what combinations are good.

Things are less clear on the other end of the spectrum with combative planting other than saying these plants don't do well together. What im curious about is in a combative situation, do both plants suffer, just one? Probably varies depending on combination.

A particular combination I've been thinking about is beans and allium. I can see where the allium would prevent the beans from producing but I know that allium like nitrogen and beans supply it. Seems like a one way battle. Any experience or suppositions on what would happen? The beans would be a sacrifice crop in this case but would the allium benefit?

 

[Meadowlark]

There are also charts available to address non companion enemies. Burpee has a very good one @

Companion Planting Guide

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I do a lot of experimentation on my own. For example, this year I found a sweet pea which appears to increase the yield significantly on potatoes.

Beans and garlic/onions/shallots would be enemies...neither one would do well with the other. My approach with onions is to get the N2 added to the soil in advance with cover crops of legumes and that way completely avoid the issue.