Does anyone have good, EMPIRICAL evidence that companion planting with nasturtiums works?

Does anyone have good, EMPIRICAL evidence that companion planting with nasturtiums works?

Here's why I ask....
I tried companion planting many years ago. I don't remember what plants I used but I didn't see any noticeable results so I didn't bother after that. And just like most all of you I get invaded by aphids every year. Some plants get hit hard some years and then not so much the next while other plants are only assaulted occasionally and some are truly devastated by them.

Many of my cucumbers get hit pretty hard and regularly. So I have tried to find a better solution for this problem besides just washing off the undersides of all their leaves constantly to knock down the population which takes quite a bit of time. I'm organic so my tools are limited. I've tried sprays of garlic, mint, etc, etc, etc. with no good results. It's too hot here to use Neem oil on most plants because they quickly get burnt and crispy and die. It's an oil in screaming hot sun! I've tried spraying it on at dusk and washing it off the next morning but most, but not all, plants still get crispy and die.

Lots of websites recommend companion planting with nasturtiums to control aphids so I went a little further and asked why? What good do nasturtiums do? The overwhelming answer was that nasturtiums don't repel aphids; aphids  love nasturtiums and will go to the flowers instead of the cucumbers. It's considered a trap crop.  Really? How do they know that the flowers aren't attracting the aphids to the cucumbers? Inquiring minds want to know!

So I devised an experiment. I love science. I planted a bunch of nasturtiums in pots early this summer. Only one of my 3 plantings of cucumbers began getting hit hard with aphids in July. (no ants, just aphids) So I took some pots of nasturtiums and set them out among those cucumbers....and waited. Would the aphids abandon the cucumbers for the flowers? Didn't happen. The aphids never went to the nasturtiums, they loved the cucumbers way too much.

So I am now trying it on artichokes. 3 of my 12 artichoke plants are being bothered by aphids this fall (again, no ants, just aphids)  so a month  ago I set the pots of flowers next to them. I still see no results. I guess my artichokes are pretty tasty too. I can use Neem oil on the artichokes; they can take it without getting burnt but these plants and my yard are still full of bees and I would rather not.

Has anybody done this and had good, EMPIRICAL results? Not just anecdotal... (didn't see too many aphids this year).... but really good results. Just curious. Or have you found something else that your sure works really well. Again, empirical evidence would be great. Thanks.

I personally don't put much stock in tales of companion planting. Seems to me there are just way too many variables at play. For example I've heard tomatoes love basil. I do grow tomatoes and basil together because we like those flavors together and it's easy to pick a tomato and a basil leaf and have an instant snack. I have however seen no evidence at all that either of those plants grows better with or without immediate proximity. I figure it would take many years of running experiments, in many varied locations and with many different varieties of these two species to establish if a benefit or deficit is actually related. I'm not going to do that and I'm unaware if anyone has, despite the claims.

That said and I apologize as this is just anecdotal, I do see benefit from what I might call confused planting.  I have a lot of volunteer vegetables in my garden which I often leave in place. Also, especially switching to no till where an entire bed is not necessarily planted all it once in the same crop. Kind of what has evolved is a largely haphazard mix of my planting. In the old days I would have had a bed of squash, a bed of cabbage and so on. Now I may have just as many plants of those vegetables but the they might be scattered all over place.

It appears and again just anecdotal, that I have less problems with all diseases and bugs, even animals and birds. Not that they are eliminated just that they don't seem to take hold and ruin a whole crop as easily. And they are easier to combat, if for example a squash plant is attacked it can be removed and the pest destroyed and often it's just that one plant involved because it is the only squash plant in the immediate vicinity.

My theory is planting this way in effect serves first as camouflage, hiding a host plant from a pest that prefers it. Second it stops the spread to adjoining plants early on so infections can be eliminated before they get a good foothold. I also believe that letting a weed or two grow here and there helps too.

Mark Reed wrote:I personally don't put much stock in tales of companion planting. Seems to me there are just way too many variables at play. For example I've heard tomatoes love basil. I do grow tomatoes and basil together because we like those flavors together and it's easy to pick a tomato and a basil leaf and have an instant snack. I have however seen no evidence at all that either of those plants grows better with or without immediate proximity. I figure it would take many years of running experiments, in many varied locations and with many different varieties of these two species to establish if a benefit or deficit is actually related. I'm not going to do that and I'm unaware if anyone has, despite the claims.

That said and I apologize as this is just anecdotal, I do see benefit from what I might call confused planting.  I have a lot of volunteer vegetables in my garden which I often leave in place. Also, especially switching to no till where an entire bed is not necessarily planted all it once in the same crop. Kind of what has evolved is a largely haphazard mix of my planting. In the old days I would have had a bed of squash, a bed of cabbage and so on. Now I may have just as many plants of those vegetables but the they might be scattered all over place.

It appears and again just anecdotal, that I have less problems with all diseases and bugs, even animals and birds. Not that they are eliminated just that they don't seem to take hold and ruin a whole crop as easily. And they are easier to combat, if for example a squash plant is attacked it can be removed and the pest destroyed and often it's just that one plant involved because it is the only squash plant in the immediate vicinity.

My theory is planting this way in effect serves first as camouflage, hiding a host plant from a pest that prefers it. Second it stops the spread to adjoining plants early on so infections can be eliminated before they get a good foothold. I also believe that letting a weed or two grow here and there helps too.

I agree.  I plant in polycultures, but I've never seen anything to convince me that any two plants grow better next to each other than any two other plants, barring the obvious like not planting next to a walnut tree.

Ah, polyculture! that's the word I was looking for. Thanks

We've companion planted Nasturtiums. I'm not sure the vegetable saw any benefit. But the nasturtiums sure loved it. They grew and bloomed all over from June until November. They self-seeded like crazy so it was the same story the next season. This greatly encouraged my wife. We could come out to a garden ravaged by slugs. But at least there were a bunch of nasturtiums. For that benefit alone we continue companion planting them.

I used to plant kale for my chickens (never really cared for it myself) and had nasturtiums in an adjacent raised bed.  Nasturtiums would be covered in aphids with only limited aphids in the kale.  I eventually ran out of nasturtium seeds and didn't bother buying any more of them and the following years, my kale was covered in aphids. The chickens didn't mind, so I didn't mind, but that's my completely anecdotal evidence that they do in fact attract aphids, however I wouldn't ever grow them mixed in with the kale.  

I also have nasturtiums. I never even considered they would help with the aphids! they are interplanted with a bunch of other stuff and are generally really happy.
I notice aphids appear in my garden on drought stressed plants, during winter as well as summer. On some plants (green onions) they will appear only during dry spells and then just naturally disappear after. On my collards and kale, they will appear and depending on whether rain actually comes or not, may stay long enough to kill the plant.
I spray with a garlic/soap spray, not with anything oil (like you, I've fried too many plants). I macerate a clove of garlic, let it sit in oil overnight, strain it out, add a tablespoon or two of liquid soap, then add a liter of water. That gets diluted down onto a spray bottle and I spray it at the end of the day, and I also remove the leaves that are really, really infested and throw them in the bokashi bucket. Or, if the plant can stand it, I may blast it with water to get the majority of the aphids off.

It seems that serious gardeners' and growers' observations are quite valuable, as long as they've actually personally observed a phenomenon.  "Empirical" might be looking for some kind of greater-than 90% probability, or guarantee that something "always" happens, or something "never" happens?  There are probably too many variables in everyone's growing circumstances to get anything near a guarantee.

I second the observation that aphids happen as a result of stress.  Something is not happening consistently (key word)  for those plants, whether it's watering or nutrition or invasion by rodent tunnels (even if it's moles who are just causing root-stressing wind tunnels,) or plants in too many hours of direct, hot sun when they really can't take that, or plants that want many hours of hot sun get too much shade, or too much wind, or different weather conditions each year, etc.  I  noticed just this summer that ant colonies can get in around the perimeter of the roots of plants and create real stress, even though the plant is getting enough water to do just fine if the ants weren't there.  Everyone's circumstances are different.


Companion plants rock, especially garlic, especially nitrogen fixers, especially herbs and flowers that bring in beneficial insects and pollinators at the appropriate times of the year.  Companion plants are not just about getting more of a crop out of something,  they are about keeping the whole ecosystem healthier, improving the soil, creating habitat.   There are blooming plants that are companions for honeybees and birds, not just for other plants.  There are plants, like comfrey, that send down deep roots and accumulate minerals that other roots don't get down to.  There are roots that allow fungi that help other roots.  It's much bigger than two plants next to each other supposedly doing what we have in mind.  They have their own lives to live, and they are not aware of what we humans need *s*.

There are also plants that don't like each other and will cause growth inhibition.  Look under a redwood tree or a red cedar tree, not much grows under there, maybe a fern or two, but there's a whole lotta inhibition going on there.  What not to plant together is just as important as what to plant together.

Isn't Permaculture all about observing nature and noticing how plants help each other?  Nature doesn't put all one type of plant over there, and another type of plant way over the other way.  It's all mixed up.   When observing which groups or guilds are the healthiest, those are the companions we want to emulate in our own gardens because for a gabillion years it's worked for Ma Nature. *s*

Here's at least one report:   https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1295&context=farms_reports

Hello Everyone,
Thank you all for taking the time to share your observations. You are such good people. I plant so many different things that I limit myself to just 6 of each variety and they all get rotated around each year and planted together in different beds to cram in as much as possible. I mostly focus on providing shade here in the blazing sun.

And John, your post was just one sentence long but IT WAS AWESOME!! I read the report from Iowa State University and my first reaction was... Yes! Some Empirical evidence!! That's what I was hoping for. Simple research studies like I had done.

Was a little bummed that there was no mention of aphids but quickly realized they had done a short, one summer study on the effects of marigolds, onions, nasturtiums, thyme and basil on broccoli, cabbage, lettuce, tomatoes and zucchini. Apparently, their main pests were cabbage worms and cabbage loopers. No aphids. Darn. Their findings indicated that onions, nasturtiums, basil and thyme seemed to help cabbages by warding off these pests. The marigolds, onions and nasturtiums seemed to help the broccoli but the thyme might have been it's  best protector. And the onions, nasturtiums and thyme might have helped the lettuce. None were perfect but every little bit helps.  It was a short study but exactly what is so helpful.

I usually see just a few cabbage worms and loopers in my garden each year but this past summer I saw a lot of them and it was the first time in 11 years that they attacked my lettuce. Nothing has ever bothered my lettuce before. These are experiments that I am eager to try next summer to see what happens. They also mentioned cucumber beetles bringing bacterial wilt to the zucchini. This was the first summer that I ever saw a cucumber beetle in my yard and there were lots and lots of them. Even though I didn't see any damage that they caused directly I did have two of my bean patches that were totally consumed by bacterial wilt. Luckily I spaced out my 6 different bean patches so they wouldn't get crossed and the other 4 weren't effected.

I wanted to know if they tried the experiment again for more conclusive evidence. (Unfortunately, they didn't)  BUT....on page 1 it says....'Follow this and additional works at.... (I clicked that link- which I  can't seem to reproduce here but you can on the report)  so I did. WOW!!! Iowa State ROCKS!!  They have hundreds of research papers going back to 2001 discussing all the subjects we discuss every day! Bugs, biochar, herbicides, cover crops, etc. etc.!  They don't just talk the talk... they do the research! I will spend the winter reading up on lots of their studies to see what I would like to try next summer.

Thank you John for that amazing information!

I am sure this is far from being "EMPIRICAL evidence that companion planting with nasturtiums works?" though this article by the Oregon State University is about a lady that has been gardening for 50 years and has some great points.

https://today.oregonstate.edu/news/practice-good-neighbor-policy-garden-try-companion-planting

Since you mentioned aphids, this lady says garlic will repel them.

Here is what she says about nasturtiums:

Apparently, squash bugs are deterred by the odor of these plants. She also puts vine-like nasturtium among the vines to confuse the bugs, which will go for the nasturtiums thinking they are squash.

This article is well worth reading just for her knowledge of what plants repel what bugs.

Along with my post above and Anne M.'s addition, here is a link that may be followed up with some Emails and phone calls to those involved.  It's on the opposite side of the state that you are at, Debbie Ann, but when possible if you can find research data (from University of Arizona or some of the USDA research stations there) that documents success in your region/climate, that can be even more powerful in your growing years ahead.  Seems the information in this link already is corroborating the information from the Oregon State and Iowa State University trials.  Good luck!

https://cals.arizona.edu/cochise/mg/best-enemies-brief-guide-companion-planting-part-2

Anne and John, I thank you both very much for your contributions. Goodness, you're the best. But John, I'm afraid I can't agree with you about the University of Arizona. My garden is now walking, talking proof that nasturtiums do NOT repel aphids or potato bugs. At least not here. And you'll notice that the UofA doesn't say they have done any research on this subject. Again, they're just passing on anecdotal advice without doing any research at all. They do that a lot.

In fact I've never seen any research papers from UofA. Probably because Arizona spends so little money on education I suspect. In fact, I had several conversations with my UofA county extension agent some years ago and he refused to believe that pill bugs (potato bugs) ever ate growing plants. He insisted they just ate rotting debris. My garden was attacked by millions of them back in 2012 and they ate damned near everything. I had plenty of pictures to prove it. And it took me 6 years to finally get them under control.

I remember calling their office back in 2014 and asking the 'master gardener' on duty if there was a way to stop ants from killing my tomato plants. They had killed 6 already. She insisted emphatically that ants do not kill tomato plants, they were just farming aphids into them. I explained that, no, they weren't farming aphids. In fact there wasn't a single aphid on any of the plants. They were climbing 8-12 inches up the stem of the tomato plant, drilling a hole in it and hollowing out the stem, one by one carrying the pulp out until the plant died. She insisted I must be wrong and asked if I had any pictures. I said that she should look at her email. I had already sent her the pictures! She was stunned to learn that I was right. A week later she contacted me to say that she had found several other people in the area that had the same problem and had also sent her pictures. So I seldom put any faith in their counsel.

I have read some really great research papers from the University of Washington and the University of Michigan is terrific too but not nearly as awesome as Iowa State. Thank you again so much for the great  information.
Happy, happy gardening everyone.
Debbie

A couple of random tidbits here...

First, nasturtiums are just all around great, you should plant them just because they are nasturtiums!. They are great ground cover, keeping you soil covered and cooler, the flowers are beautiful and edible, leaves are a peppery addition to salads, and... capers! Or, not quite capers, just the seeds that the plant produces so abundantly, looking like green garbanzo beans/chickpeas. Just throw them into vinegar for 3-6 months and you'll have something that for me really closely resembles the taste of capers.

And, regarding aphids. I do agree that aphids seem to attack stressed plants a lot, so keeping your cukes really well watered, especially in your climate, might be very useful. But honestly, sometimes they just come. So of course attract all the ladybugs you can and purchase some more if you can't, they eat huge quantities. But also, I have a secret formula that has worked wonders for me.

It uses what I think are the shredded roots of a plant you may be able to find in at an herbalist's. The plant is called Quassia Amara. I was turned on to this by an Argentinian who stopped into the local health food shop. People were discussing that there was an outbreak of head lice in the local elementary school and the parents were going crazy trying to find some non-toxic way to remove the lice. And the Argentine guy recommended this quassia amara, saying they use it for that, and also for things like aphids on plants. My ears perked up as I had aphids on my kale at the time (I was trying to grow a Siberian kale and my climate is really too warm for it.)

So I ordered so quassia amara for my plants and the shop owner ordered some for their daughter, and it worked for both of us! But you have to be careful preparing it. Here's the deal:

Take 2 generous tablespoons of quassia amara
(it looks and smells like shredded licorice root)
Put in a pot with 500-750 ml of water
Boil, covered, for 30 minutes, no more, no less
As soon as it cools, strain it and filter it through an old stocking to remove ALL of the solids
Pour it into a spray bottle and spray away.
Use it all NOW -- it is completely useless 24 hours later.
(My theory is that the liquid is a bit sugary and sticky, which is what kills the aphids. In 24 hours, it ferments. The smell is very different the next day, and it doesn't work.)

I sprayed it on my kale plant and it looked like nothing was happening, so I went home dejected. Came back two days later and at one point gardening I said, hmm, what's that funny grey circle on the ground under my kale plant? And lo and behold, on closer inspection, it was a carpet of dead aphids.

So since then, I am a member of the church of quassia amara. It seems to work for all kinds of little critters. But also, I look for other varieties of plants that once got attacked by aphids. So now I grow a couple other types of kale, and for instance maybe you can find some cucumbers especially adapted to hot climates or something. Just a thought.

Thank you Dave for your random tidbits!

Wow! I am seriously enjoying this discussion! I wish you could all hear my applause. Yes, I understand how stress can effect the plants but unfortunately I live in high desert country where it is 100* to 113* for about 5 months of the year. Everything here has to learn to deal with it, including me. That's why I plant cool weather crops here all winter. The last 3 years I have been experimenting with vegies from the hottest parts of the world. I've been growing tomatoes and cucumbers and eggplants and many other things that have originated in places like Africa, a kibbutz in Israel, Iraq and Texas. Most of them are doing really quite well. It is a good and tasty experiment. But they are just as susceptible to bugs and diseases as our American vegies.  

I've managed to overcome lots of issues. I'm just trying to focus on empirical evidence now instead of wasting so much time on hit or miss theories. I'm getting old. I don't have so much time to waste any more. Quassia amara sounds like a really interesting plant from tropical South America. A quick read on Wikipedia shows it has a lot of promise as an insecticide and medicinal uses with caution. It's available here in the U.S and apparently it's allowed in organic gardening! But I can only find it for sale as a health supplement. None of the companies that I buy my organic supplies from has ever heard of it! I will get creative by next summer!

And hey, I think we need to all get more proactive about saving the rain forests!!!

Thanks again.

Great Debbie, so I kinda figured that you were on the ball and were watering very well and sourcing hot climate varieties, but I put it out there just in case. Good for you!

A while internet sleuthing managed to turn up a US supplier that seems to have what I use here. It's a South Asian and Middle Eastern spice shop in New York! You never know where you're gonna find your next ally. Here it is:

Quassia Amara "wood chips" at Kalustyan's (spices teas & sweets - Manhattan)

That's not what I would call wood chips, but whatever, there you have it!

Happy spraying

I'M ON IT!  THIS MIGHT BECOME AS HELPFUL AS NEEM OIL OR SPINOSAD!! THANK YOU VERY MUCH DAVE.

Thanks a bunch for the recommendation about Quassia amara.
Here's my contribution: this plant is widely used across Latin America in herbal medicine (stomachaches, diabetes, worms/parasites) and by people who make their own spirits (it's delightfully bitter). We call it pau tenente where I live and it's available everywhere.
If you have access to botanicas or other places that sell herbs to people from Latin America you might find it under other names:
hombre grande (Costa Rica); cuasia (Mexico); hombre grande, palo grande (Guatemala); cuasia, hombre grande, limoncillo, tru (Honduras); hombre grande, chile de río, chirrión de río (Nicaragua); guabito amargo, crucete, hombre grande (Panama); cuasia, bitter-ash (West Indies); cuasia amarga (Bolivia); pau quassia, quina, falsa quina, murubá, murupa (Brazil); cuasia, creceto morado, contra-cruceto (Colombia); quashiebitters, quassia-bitters (Guyana); amargo, cuasia, simaba (Peru); surinam quassia (English).

Thank you Tereza, That's good to know. Have you ever tried it?

I have already ordered a pound for $8.36 plus another $8.40 for shipping. Which is still cheaper then most of the organic products that I use!  I'm just bummed that I have nothing to try it on until next summer! This reminds me so much of Neem oil. I think we began hearing about Neem oil back in the late '70s. And by then damned near everyone else on the planet had been using it for years! U.S. Americans can be so clueless sometimes. Does anyone have a cure for that? I'm all ears!
Thanks again everyone,
Debbie

Debbie Ann wrote:Have you ever tried it?

I've tried cachaça made with it, i had a friend who was really into making their own funky concoctions. Didn't notice any special effects but it tasted great.