Companion Planting - Does it work?

So, I’ve read in a number of places about companion planting for trees. Using nitrogen fixers like clover, or supposedly a variety of possibly pest or fungal repellent plants.

Does this actually work, or is it just new age organic pesudoscience?

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Companion plants are a means for nurseries to sell more plants. It is a marketing ploy which caught on with consumer gardening publications. Of greater interest are indicator plants which become stressed prior to the majority of your garden or orchard.

Nitrogen fixing plants do not put nitrogen in soils, but rather enlist specific soil microbes to “fix” (preprocess) nitrogen sources on their behalf. Here’s a post on the subject from awhile back: Diversity among Nitrogen fixing plants

“Cover crops” is a valid topic from which marketing of companion plants evolved. The purpose of a cover crop is to suppress unwanted growth (i.e. weeds) between rows of orchard trees or rows of annual produce. Typically the “cover crop” is tilled under after harvest. The cover crop is very specific to the target crop you are growing, plus your local soil and climate. Sometimes it has benefit beyond weed suppression but usually not.

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Yeah, I knew that about nitrogen fixing plants. Frankly, it seems like a waste for perennial plants since you have to till the plants into the soil. But advice like this seems so common.

That and I’m getting tired of pulling carpet weed out of my mulched bed.

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Because advertisers are quick to offer “relief”. I recommend you work smarter. In particular, I now have zero weeds.

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[quote=“TheGrog, post:3, topic:12146”]
for perennial plants since you have to till the plants into the soil. But advice like this seems so common.

That and I’m getting tired of pulling carpet weed out of my mulched bed.
[/quote]Yes and no, like planting some plants close to some others can poison other plants, some plants repel insects or distracts insects from more important plants, yet just like a lot of things in the world the truth has to be separated from the fiction, that is how the world is. Like for example marigolds repels lots of insects and attracts others. Ever since marigolds were planted near our fig trees there have been no ants anywhere near our fig trees. They also are repelling woolly aphids. I am looking forward to next year to see if can really repel slugs. We have lots of them in the spring.

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In your locale. And it might have nothing to do with the marigolds but rather how you disturbed the soil or the marigold hybrid. It makes no difference in mine.

“One data point does not make a statistic.”

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There is some research, but not a lot. And what there is, is often misapplied. For instance, one type of marigold, when planted in an entire bed for an entire season and then tilled under,was shown to decrease nematodes the following season. From this one very specific result, people generalised “marigolds repel pests.”
As for perennial polyculture, there are a few studies started, but not much. Research takes time and money, and most of those interested in perennial polyculture have neither.

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Comfrey serves as a living mulch around many of my fruit trees, the thick roots do not occupy the same soil niche as finer tree feeder roots, leaves smother and shade out grass, provide beneficial insect habitat, flowers attrace pollinators, leaf and root decay enriches soil. Many other uses for this valuable plant as well- compost ingredient, tea made from leaves, livestock fodder, herbal remedies etc.

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I use lettuce in fig containers sometimes

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Trees occupy primarily the top 18" of soil with their fine feeder roots- are you saying that comfrey extracts water and nutrients only below 18"? I know that Russian comfrey sends roots much lower and brings up nutrients that can be used by other plants if you cut it and leave the residue, but this doesn’t mean it does not compete in the more nutritious and better aerated top soil. In the humid regions, there is also the question of what pests it may attract as broad leaf weeds often attract damaging plant bugs.

I would want to be sure ahead of time about the consequences because it seems that comfrey can be hard to kill once established.

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[quote=“Richard, post:6, topic:12146”]
In your locale. And it might have nothing to do with the marigolds but rather how you disturbed the soil or the marigold hybrid. It makes no difference in mine.

“One data point does not make a statistic.”
[/quote]Before the marigolds nothing got rid of ants or aphids except insecticide. Even if the soil was disturbed that would not keep the ants away. Out of the 6 years we have had fig trees the ants would be all over the fig trees and be in the figs, had to wash them out. Universities promote companion planting, companion planting has been traced back to about 10,000 years ago, of course some people take advantage of companion planting to sell more plants, it’s very hard to survive as a nursery, yet it would not have been around for like 10,000 years if there was not something to it.

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Since studies usually contradict each other on the same topic i never trust them fully, I suspect that the toxic roots of Marigolds when attacked by nematodes leaks it’s natural pesticide in to the soil and that is what keeps the ants away, I looked todday and the ants are in the soil sort of near the marigolds, yet they are staying away from the soil near them, this article talks about how Marigolds stops nematode problems, it does not repel them it kills them with the Marigold’s natural pesticide http://blog.nola.com/dangill/2008/05/the_truth_about_marigolds.html

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No, but cover crops have. “Companion planting” has a completely different meaning in “organic lifestyle magazines” than we have in agriculture.

[quote=“Richard, post:13, topic:12146”]
No, but cover crops have. “Companion planting” has a completely different meaning in “organic lifestyle magazines” than we have in agriculture.
[/quote]Interesting!

I have zero ants on my fig trees because every few days I remove damaged and overripe fruit to a greenery bin on the other side of the property.

[quote=“Richard, post:15, topic:12146”]
I have zero ants on my fig trees because every few days I remove damaged and overripe fruit to a greenery bin on the other side of the property.
[/quote]For us the ants are usually waiting for the fruit on the tree, even before the figs start forming waiting for them to split or the birds to peck them open.

I think several distinct (albeit related) concepts are being confused in this thread.

The use of nitrogen fixers to benefit adjacent crops is a pretty widely accepted and supported practice. We understand how these crops fix nitrogen, it’s not a pseudoscience. there are reams of university publications on this in the fields of pasture management, lawn management, etc. Clovers don’t need to be tilled under in these context to benefit adjacent plants - just mowed or grazed. As it relates to orchard management, having nitrogen fixers adjacent to, in the rows, etc of fruit trees, mowing them and depositing as mulch is an indisputable source of nitrogen to trees - both below ground where leguminous roots are shed and decompose and above ground where the mulch decomposes.

Providing habitat for beneficials: “science” knows for a fact that there are beneficial insects in our orchards that predate and pariticize harmful insects. We know that those beneficials require certain plants for habitat, pollen and nectar to survive. if you frequently spray broad spectrum insecticides (excluding targeted sprays such as neem or BT, etc), this is all moot because you’ve likely eliminated beneficials from your orchard. But if you don’t spray, providing habitat for these is critical in my opinion.

“Companion planting” as I believe it is typically used in organic literature: dill planted next to tomatoes, sage next to potatoes, etc. I believe this is mostly annectdotal and don’t understand the science behind it personally. But why not try it? If you have a garden you’re probably growing the herbs in question already, it’s just a matter of location. If not it’s a couple bucks worth of seed. It’s a stretch to claim its some kind of money making conspiracy / marketing ploy… A packet of dill seed isn’t where they make their money. Probably much more money made in the “-cide” aisle…

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Bleack!

That would depend on which insecticides and where you spray. The judicious use of pesticide should target pests not most of the insects in the vicinity. A certain amount of collateral damage is inevitable, but if we are talking about home orchards, the amount of pesticide required to stick a crop should not eliminate a wide diversity of insect inhabitants including beneficial predators. Many beneficial predators can survive even direct exposure to the insecticides I use on my trees- I select them for that purpose and Cornell does not recommend the use of any insecticides that create that kind of a wide swath of elimination except in emergencies when no other solution is available- like when BMS infests your orchard.

What you suggest isn’t “absolutely false” but it isn’t absolutely true either.

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My specific issue is that I planted a mixed row of marigolds, lavender, tansy, and onion chives on the border of my berry bed. Most of those are annuals, I’m not sure I want to continue buying and planting those every year.

Second, I’m getting tired of plucking carpet weed. I idly thinking that a groundcover of clover might be useful but the spacing is narrow enough that I’m not sure I can get the mowing/tilling necessary and that it would still compete with the berry plants for water & nutrients.

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