If you’ve been gardening for any amount of time, you’ve likely come across companion planting charts—maybe you’ve seen advice like “plant basil with tomatoes” or “marigolds repel all pests.” But how much of this is actually true?
Companion planting can mean a lot of things, depending on what our goal is. We can either be going for pest repelling properties, keeping weeds down, soil health benefits, or just enhancing flavors or saving space.
Today on Just Grow Something, we’re sorting fact from fiction. Some companion planting practices do have solid science behind them. But many claims are more anecdotal than evidence-based—and in some cases, well-intended pairings might even backfire. I’m looking at you marigolds. Let's dig in!
References and Resources:
Save 20% on your new own-root rose plant at HeirloomRoses.com with code JUSTGROW https://heirloomroses.com
Companion Planting: Fact or Fiction?: https://growappalachia.berea.edu/2019/04/01/companion-planting-fact-or-fiction/
Companion Planting & Botanical Pesticides: Concepts & Resources: https://attra.ncat.org/publication/companion-planting-resources/#4
Companion Planting | West Virginia University: https://extension.wvu.edu/lawn-gardening-pests/gardening/garden-management/companion-planting
Phytoremediation episode: https://justgrowsomethingpodcast.com/episode/focal-point-friday-are-sunflowers-good-or-bad-for-the-garden
IPM episode: https://justgrowsomethingpodcast.com/episode/integrated-pest-management-in-the-home-garden-ep-228
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00:00:00
If you have been gardening for any amount of time, you have
00:00:03
likely come across companion planting charts.
00:00:07
Maybe you have seen advice that says plant basil with tomatoes,
00:00:10
or just general advice to plant marigolds with everything
00:00:13
because they repel pests. But how much of this is actually
00:00:17
true? Companion planting can mean a
00:00:20
lot of things. Depending on what our goal is.
00:00:23
We can either be going for pest repelling properties, or we
00:00:27
could be aiming to keep weeds down.
00:00:30
We might be looking for soil health benefits or just
00:00:32
enhancing flavors or saving space.
00:00:35
Today I'll just grow something. We are sorting fact from
00:00:39
fiction. Some companion planting
00:00:40
practices do have solid evidence behind them, or I should say
00:00:44
solid science. But a lot of claims are more
00:00:48
anecdotal than evidence based. And in some cases we might be
00:00:52
doing some well intended pairings that may even backfire.
00:00:56
I'm looking at you marigolds. So we will talk about what the
00:01:00
research says about using specific plants to either deter
00:01:04
or attract pests, when companion planting works and when it
00:01:08
doesn't, which plants shouldn't be grown together and of course
00:01:12
the why behind that. And we'll touch a little bit on
00:01:17
using intercropping effectively in the home garden.
00:01:20
We are going to bust some myths and set the record straight.
00:01:26
Let's dig in. Hey, I'm Karen and what started
00:01:29
as a small backyard garden 20 years ago turned into a lifelong
00:01:33
passion for growing food. Now as a market farmer and
00:01:36
horticulturist, I want to help you do the same.
00:01:39
On this podcast, I am your friend in the garden teaching
00:01:42
evidence based techniques to help you grow your favorites and
00:01:44
build confidence in your own garden space.
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So grab your garden journal and a cup of coffee and get ready to
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just grow something. Before we jump in, I want to
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shout out my patrons over on Patreon for their continued
00:02:00
support of this show by either supporting my coffee habits or
00:02:05
just supporting the show itself with monthly support.
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I wanted to shout out our newest patron, Robin, who joined at the
00:02:12
BI Karen. A coffee level keeping me
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caffeinated is a very good thing for everybody involved.
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Trust me. And I truly appreciate you Robin
00:02:20
and all of my other patrons who support this show monthly.
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And for those of you who have did to jump on to buy me a
00:02:27
coffee and send over a one time support in terms of a coffee or
00:02:31
three, if you are interested in supporting the show, you can do
00:02:35
that from patreon.com/just Grow Something or Buy Me a
00:02:39
coffee.com/just Grow Something. I will link to both of those in
00:02:43
the show notes. It absolutely means the world to
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me when I get feedback from my gardening friends that tells me
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that the content here is resonating with you and that you
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are getting value. So thank you.
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Thank you very, very much. So companion planting kind of
00:03:04
gets framed as this sort of magic bullet for pest problems,
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but the reality is a little bit more nuanced than that.
00:03:14
And like I mentioned in the intro, there are a lot of
00:03:16
different reasons why we might want to do companion planting
00:03:21
and what that means for us in our garden.
00:03:24
So our goals with companion planting are going to dictate
00:03:29
what plants we actually plant to together as companions.
00:03:34
True companion planting works through a couple of different
00:03:38
mechanisms. The first one would be pest
00:03:40
confusion. So we talked about that a little
00:03:42
bit last week in the pest prevention episode.
00:03:46
We're talking about masking scents or disrupting the pest
00:03:50
host location. So we talked about those
00:03:52
appropriate and inappropriate landings theory where a new
00:03:57
insect is looking for a very specific set of traits in a
00:04:02
plant to understand or to recognize that it is the place
00:04:06
where it's supposed to be laying its eggs.
00:04:08
And it will land just to kind of test out whether or not that's
00:04:12
the right plant. And then it will land again.
00:04:14
And if it lands on a plant that isn't its host, that is
00:04:18
considered, it's considered an inappropriate landing, then that
00:04:21
kind of resets the whole process and they start all over again.
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So this is confusing the past. It also can be done in terms of
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scents. And by scent we usually mean the
00:04:33
chemical signals that it's giving off, which to us that
00:04:35
smells like something very specific, but to pests it might
00:04:39
smell a little bit, you know, differently than that.
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But they're looking for very specific scents or chemical
00:04:44
signals for the plants that they normally either use as a host or
00:04:48
predate on. And if we can use companion
00:04:51
planting to mask those scents and disrupt all of that, then
00:04:55
that is going to be successful. That is a successful companion
00:04:59
planting. So that's pest confusion.
00:05:02
The second one would be trap cropping.
00:05:04
So essentially this is sacrificing 1 plant to protect
00:05:10
another one. I actually discovered a really
00:05:13
good trap crop for kale specifically like curly kale and
00:05:18
other brassicas when I planted dinosaur kale for the first time
00:05:23
and I had it in one particular field where I was planting a lot
00:05:26
of my brassicas. So I had my curly kale and I had
00:05:29
my mustards, and I had broccoli and cauliflower and cabbage and
00:05:37
bok choy and a bunch of other greens that were all kind of in
00:05:39
that same sort of family. And I planted dinosaur kale for
00:05:44
the first time. And the dinosaur kale was torn
00:05:49
to shreds. And this was before I really
00:05:52
started relying heavily on insect netting, so most of my
00:05:55
stuff was not covered at this point.
00:05:58
That dinosaur kale looked like Swiss cheese.
00:06:00
The holes in those leaves from the cabbage moths and the
00:06:04
cabbage butterflies larvae as it has.
00:06:07
So all those little caterpillars, the cabbage
00:06:09
loopers had just destroyed that dinosaur kale.
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But in the process of them doing that, the majority of my other
00:06:17
brassicas were being left alone and that was my first time
00:06:21
really discovering the truth behind trap cropping and it was
00:06:26
attracting the pests away to their preferred crop and using
00:06:32
that crop as a way to draw them away from the other things that
00:06:34
I was trying to grow. My attempt this year at trap
00:06:39
cropping is for my zucchini and my yellow squash.
00:06:42
So I am going back to a traditional method of of trap
00:06:47
cropping for zucchinis and other squashes and that is using blue
00:06:53
Hubbard squash. So blue Hubbard squash is
00:06:56
another one that is a preferential plant for
00:06:59
everything that's in the squash family.
00:07:02
The squash buying bores and the cucumber or the the squash bugs
00:07:06
absolutely prefer the blue Hubbard squash plant for
00:07:10
whatever reason over the other ones that we will grow.
00:07:13
So the key here is to get the blue Hubbard squash to be a few
00:07:17
weeks more mature than the other plants.
00:07:19
And so the plan is to get the blue Hubbard squash planted out
00:07:24
in one bed and leave it uncovered.
00:07:27
I'm also going to plant marigolds at either end, which
00:07:31
you'll find out why here in a minute.
00:07:33
And then I'm going to plant sunflowers a little bit away
00:07:38
from that crop. And then on the other side of
00:07:41
that particular field is where I'm going to plant my zucchini
00:07:44
and my yellow squashes and my other summer squashes, which
00:07:48
will immediately be covered with insect netting.
00:07:53
And I will have nasturtiums at either end of those beds.
00:07:56
And then a little ways away, I'm going to have more sunflowers
00:07:59
in. Now, the idea is that the insect
00:08:02
pests are going to be more attracted to the blue Hubbard
00:08:04
squash #1 because it's going to be a little bit more mature and
00:08:07
#2 because it is the preferred crop #3 it will not be covered.
00:08:12
And so it'll be an easier target for those pests.
00:08:16
In addition to that, the sunflowers hopefully are going
00:08:19
to attract birds to feed on the sunflowers, which also are going
00:08:25
to feed on the insect pests that are in the blue Hubbard squash,
00:08:29
which will be very close by. And the idea here is that all of
00:08:33
those pests will go over to the blue Hubbard.
00:08:35
And so when it's time to uncover the yellow squashes and the
00:08:38
zucchini on this side, because obviously they have to be
00:08:41
uncovered in order to be pollinated, then it'll be less
00:08:44
likely to attract those pests to the other side.
00:08:48
I'm not thinking that this is going to completely, 100%
00:08:51
protect my zucchini in my yellow squash, but it's hopefully going
00:08:54
to draw away the majority of those insect pests and get them
00:08:57
over to the blue Hubbard. Now with trap cropping it, it
00:09:00
may not necessarily be just about drawing them away.
00:09:03
You might use it literally as a trap.
00:09:06
You're trapping these pests by in some way eliminating them
00:09:10
once they are in that crop. So this might be pulling that
00:09:14
crop completely and getting rid of it and the pests along with
00:09:18
it. This might be spraying something
00:09:21
like an, you know, insecticidal soap or something to knock that
00:09:24
insect pest population down so that they can't go over and
00:09:28
predate on your other ones. There's all kinds of ways to do
00:09:31
this, but that's the essential idea behind trap cropping.
00:09:34
Another way that we can effect companion planting is through
00:09:38
allelopathy. And allelopathy is basically a
00:09:42
plant that exudes chemical signals oftentimes either
00:09:47
through their roots or through their plant tissue that inhibit
00:09:52
some other growth or that do something with those chemicals.
00:09:57
So for example, with marigolds, we're talking about them
00:10:00
exudating a a root exit called thiopine that has been shown to
00:10:07
suppress root, not nematodes, right?
00:10:09
For sunflowers, this is going to be them keeping weeds at Bay.
00:10:14
So we'll talk about that a little bit more in depth.
00:10:15
But that is another way that we were, we would use companion
00:10:19
planting as a way to help prevent things or accomplish
00:10:23
things in the garden. And then we also can use
00:10:28
companion plants for attracting beneficial insects.
00:10:31
So this might be more of an idea of we're going to plant these
00:10:35
things in order to bring in natural predators or to bring in
00:10:39
more pollinators in order to help us combat some of the other
00:10:43
things that are going on in our garden.
00:10:45
You could also look at some of the inter planting that we do
00:10:50
and use and consider that some companion planting, especially
00:10:54
when in terms of maybe we're having some of the plants act as
00:10:57
a living mulch. So think about the three sisters
00:11:00
method, OK, if you're not familiar with the three sisters,
00:11:03
essentially it is a traditional way of growing three specific
00:11:06
crops. You're growing corn generally.
00:11:09
We're not talking about sweet corn here.
00:11:10
We're talking about dent corn or flour type corns.
00:11:13
So this is a dried corn, which means those stocks are going to
00:11:16
be out there for an extended period of time.
00:11:18
But at the same time you are planting beans, whole beans, at
00:11:22
the base of those corn plants so the beans can climb up the corn.
00:11:27
And then you are planting pumpkins or some other type of a
00:11:30
winter squash in and amongst the corn and it is crawling across
00:11:34
the ground and it is suppressing weeds.
00:11:36
So in this instance, this is a companion planting technique
00:11:40
that has nothing to do with keeping predatory insects out.
00:11:45
This is all about one plant supporting the other, supporting
00:11:48
the other, right? The the corn is acting as a
00:11:50
trellis for the beans. The beans are fixing nitrogen
00:11:53
into the soil that the corn really needs for its growth.
00:11:57
And then the squashes are vining in and amongst all of those
00:12:02
plants and they are providing ground cover which is helping to
00:12:05
keep the weeds at Bay. So not all companion planting is
00:12:09
specific to insect pests. It can be, but we just just want
00:12:14
to understand what mechanism we are interested in when we are
00:12:18
deciding what to plant with each one of our crops.
00:12:22
OK, so that's the first thing. But a lot of companion planting
00:12:28
charts are aimed at, you know, insect pests, and a lot of them
00:12:35
really rely very heavily just on anecdote.
00:12:38
And there isn't really any scientific backing to them.
00:12:42
This is not to say that it's not true, OK?
00:12:46
We've talked before about, you know, there's a difference
00:12:48
between causation and correlation.
00:12:50
And you know, us planting, you know, our basil with our
00:12:54
tomatoes and it's seeming like it the tomatoes tasted better
00:12:57
that year doesn't necessarily mean that's actually what
00:12:59
happened because there are so many other factors that could be
00:13:02
going on in our yards. This also doesn't mean that even
00:13:07
if it is backed by science, that it is necessarily going to work
00:13:10
for you in your garden because your soil type, your climate,
00:13:16
your amount of rainfall, all of those things are going to affect
00:13:22
how plants perform. And you know what type of
00:13:26
chemical signals or how strong the chemical signals are that
00:13:29
they give off. It's a lot of scientific based
00:13:32
information is based in a laboratory setting where things
00:13:35
are very well controlled. And as you have probably
00:13:38
experienced as a gardener, nothing is well controlled in
00:13:42
our gardens. Even when you find science
00:13:45
backed information, always think that you know, you should be
00:13:48
taking that with a little bit of a grain of salt and
00:13:50
understanding that it it may not work as well for you in your
00:13:53
garden as it did in the research garden or the research plot.
00:13:57
OK, so let's look at some popular companion plants and
00:14:01
what the research actually says or doesn't say about them.
00:14:05
And the very first one that we're going to talk about is
00:14:07
marigolds, because this is still probably one of the most
00:14:12
misunderstood companion plants in the home garden.
00:14:17
So this week I noticed my rose Bush from heirloom roses was
00:14:22
putting on a lot of beautiful green leafy growth.
00:14:25
And then I wondered if there was anything specific that I needed
00:14:28
to do with the plant in terms of spring care or more
00:14:32
specifically, pruning. I have mentioned I am not
00:14:35
someone who has had very good experiences with roses in the
00:14:39
past, and I honestly have no idea when it's a good time to
00:14:44
perform certain tasks just to make sure that it's living its
00:14:47
best little rose life. thankfullyheirloomroses.com has
00:14:51
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00:14:55
best decisions for when and how to care for my rose, not just
00:15:00
now in its first full year in its pot out front, but for years
00:15:04
to come. They also provide emails every
00:15:08
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00:15:11
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00:15:16
This just makes me even more confident to go find maybe
00:15:19
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The link is in the show notes. I was one of those people who
00:15:56
recommended and used to plant marigolds with literally
00:16:01
everything in my garden. I planted them in and amongst
00:16:04
all of my zucchinis. I put them in and amongst all of
00:16:06
my cabbages and my brassicas. I put them in my tomatoes like I
00:16:09
used them everywhere. And let's be very clear, we're
00:16:13
talking specifically about French marigolds here.
00:16:16
So this is to Jetty's Pitula. You can also use Mexican
00:16:20
marigolds. They're a little bit different
00:16:22
the, the other one, not the friend.
00:16:24
The African marigolds do not work nearly as well in terms of
00:16:28
companion planting. You want the ones that really do
00:16:30
give off a very strong scent, that very particular scent.
00:16:34
The the African marigolds are very pretty, but they're not
00:16:37
really good in terms of companion planting for, for
00:16:42
specifically for insect pests. They might be, you know, good at
00:16:45
attracting pollinators and such, but not so much for insect
00:16:47
pests. OK, Like I mentioned with the
00:16:50
French marigolds, they do give off root exudates called
00:16:54
thiapine, and those have been shown to suppress nematodes.
00:16:59
OK. But when we're talking, and so
00:17:01
if you have nematodes and you have specifically root, not
00:17:04
nematodes in your tomatoes or other crops, then yeah,
00:17:06
absolutely you can use marigolds in terms of above ground crops
00:17:12
or above ground pests. I mean marigolds do not repel
00:17:17
all pests. As a matter of fact, they
00:17:19
actually are attractive to certain pests.
00:17:22
So this is where you have to decide what pest is it that you
00:17:25
want to repel if you are interplanting them amongst your
00:17:29
crops or what pests are you wanting to attract if you are
00:17:35
using it as a trap crop to draw pests away from your crop.
00:17:41
OK, so if you have problems with aphids, whiteflies, melon worms
00:17:48
and pickle worms, coddling moths.
00:17:51
So these are the moths that plague like your apple fruits
00:17:53
and your other palm fruits, those root nut nematodes,
00:17:57
diamondback moths or cabbage stem flea beetles, then yes,
00:18:03
marigolds are good at repelling those things.
00:18:07
OK, so this is something where if you have cabbage stem flea
00:18:12
beetles or you are dealing with aphids or whiteflies and you can
00:18:16
interplant marigolds in and amongst those crops that you are
00:18:20
trying to protect from those specific pests.
00:18:24
But if your pest problem involves squash bugs or squash
00:18:30
vine boars or cucumber beetles, you guys know those are my top
00:18:34
three, right? Leaf hoppers, spider mites,
00:18:38
tarnish plant bug, beet armyworm, cabbage loopers,
00:18:42
tobacco budworms, flea beetles, other than the cabbage stem flea
00:18:46
beetles. So the striped flea beetles or
00:18:48
the western black, all the other ones, right?
00:18:50
Or thrips. Then you need to be aware that
00:18:54
marigolds are actually attractive to those insects.
00:18:59
So now you know why I would be planting marigolds in with my
00:19:04
blue Hubbard squash. Because I want the squash bugs
00:19:08
and the squash vine boars to go over into those blue Hubbard
00:19:13
squashes. I want them away from my other
00:19:15
ones. The one thing that I failed to
00:19:16
mention too, is that the other thing that I'm putting over in
00:19:20
those blue Hubbard squash plants is some pheromone traps for the
00:19:25
squash vine bore. So I really want everything, all
00:19:28
those insects to go over to that crop over there.
00:19:31
And so I'm going to use the marigolds for that.
00:19:35
Now, in terms of like my brassicas where I used to always
00:19:38
plant marigolds in and amongst my cabbages and my broccoli and
00:19:43
my cauliflower, that was a really bad idea because my
00:19:47
problem is not with cabbage stem flea beetle, which is repelled
00:19:51
by the marigolds. My problem is with cabbage
00:19:54
loopers and marigolds attract cabbage loopers.
00:19:58
So that was not a really good idea for me.
00:20:01
I should be planting the marigolds away from my cabbage
00:20:04
and other brassica brassica crops.
00:20:07
So now what I do is when I plant my brassicas, I am planting
00:20:11
alyssum and I'm planting onions and I am planting lettuces and
00:20:14
intermixing all of that together.
00:20:16
And then I am covering it with that insect netting.
00:20:19
And then I am planting marigolds further away from those beds so
00:20:25
that I'm trying to draw those cabbage loopers away, right?
00:20:29
You need to plant according to your goal.
00:20:32
And marigolds are also attractive to the beneficials to
00:20:35
some of the beneficial, so like ladybugs and hoverflies and some
00:20:39
of the parasitoids and predatory insects.
00:20:41
So just plant according to your goal.
00:20:45
What is it that you are trying to achieve and use marigolds in
00:20:48
that instance? So what about like planting
00:20:52
basil with tomatoes? There actually is no strong
00:20:56
scientific evidence that basil does anything in terms of like
00:21:00
repelling tomato hornworms. As to what is often touted for
00:21:04
doing or improving the flavor of the tomato, there is anecdotal
00:21:09
data that suggests it might help repel thrips, and that maybe the
00:21:14
strong scent of the basil can help repel other insects.
00:21:19
And basil does attract pollinators.
00:21:21
This can actually be true of a lot of different strong scented
00:21:25
herbs and flowers, so this may not be specific to basil with
00:21:32
tomatoes. It doesn't mean again, that
00:21:35
these things aren't true, it just means that there isn't any
00:21:37
actual evidence. So there is no harm in planting
00:21:40
them together, but you just shouldn't rely on basil alone
00:21:44
for your pest control. So in addition to planting basil
00:21:49
in with my tomatoes, which I absolutely do, I absolutely do
00:21:52
this. I do think they go well together
00:21:55
and I will actually plant multiple varieties of basils.
00:21:58
So the green like Italian basils, sweet basils that we
00:22:01
harvest to, to sell in bunches of actual basil leaves.
00:22:05
I also plant different types of basil that maybe I'm not
00:22:09
harvesting to sell, but I'm allowing them to go to flower
00:22:12
because they do put off such beautiful flowers and a lot of
00:22:15
pollinators and other insects are attracted to that.
00:22:18
And of course that helps the tomatoes.
00:22:19
But also I am planting things like, you know, marigolds down
00:22:23
at the ends or in and amongst the the tomatoes.
00:22:27
And I am going to plant sunflowers down at the end of
00:22:30
that section of the garden to attract the birds.
00:22:32
And the birds are trying to pick off the things like the tomato
00:22:36
hornworms that might actually be damaging my tomatoes, but that
00:22:40
maybe the basil isn't repelling. I am not relying on just one
00:22:44
planting or one companion to do these jobs.
00:22:48
I am, you know, loading my bases and making sure that every
00:22:52
single thing that's out there has some sort of different
00:22:56
mechanism for helping me with these insect pests.
00:22:58
So no harm in planting them together, but don't rely on
00:23:01
basil alone for your pest control.
00:23:04
Another one would be porridge and planting that near squash or
00:23:09
tomatoes. Porridge flowers do attract
00:23:12
pollinators and they attract beneficial Wasps and some of
00:23:15
those beneficial Wasps are the ones that will predate on those
00:23:19
tomato hornworms. You may have seen images of
00:23:23
tomato hornworms with eggs laid on them.
00:23:26
It's fascinating to see. And what that is, is these
00:23:29
predatory Wasps have come in and have laid their eggs on the
00:23:32
hornworms. And when those eggs hatch, then
00:23:35
they essentially eat the hornworms.
00:23:36
And so you're kind of disrupting that hornworm reproduction cycle
00:23:40
right there. So, and there have been some
00:23:42
studies that do show if you were tomato hornworms on plants that
00:23:45
are planted near borage, You just have to remember that
00:23:48
borage grows very large, so you want to space it appropriately
00:23:51
to avoid shading anything nearby.
00:23:53
So it's fine to do them with the tomatoes because they're both
00:23:56
fairly tall. But if you're doing it near
00:23:58
squash, you want to do this like sort of appropriately, right?
00:24:02
I keep mentioning sunflowers and I use sunflowers to attract
00:24:08
birds that will predate on the insects in my garden.
00:24:12
And thereby I am helping to reduce the pests.
00:24:15
But I do shy away from planting anything too close to the base
00:24:20
of those plants because sunflower can be a highly
00:24:24
allelopathic plant. It's phytotoxic potential has
00:24:30
been shown on crops and weeds in not just laboratory settings,
00:24:35
but also in greenhouse and field trials.
00:24:38
And they've done all kinds of tests on this with different,
00:24:42
you know, a variety of factors like the concentration of how
00:24:45
many sunflowers are growing and the different species and the
00:24:47
different genotypes. So, you know, again, sunflower
00:24:51
are another one that kind of gives off these, these root
00:24:54
exudates that are chemicals that are going to inhibit the growth
00:24:59
of other plants in and around the base of the sunflowers.
00:25:03
Which means that sunflowers are a good crop to plant for
00:25:06
suppressing weeds, especially annual weeds, because it's going
00:25:10
to prevent them from coming up. But it may not be something that
00:25:12
you want to plant within a few feet of any crop that you
00:25:15
actually intend to harvest. Which it's kind of a shame
00:25:19
because, you know, we talked about the Three Sisters method.
00:25:21
And if you think about a sunflower, they have such real
00:25:25
good sturdy stalks. You would hope that it would be
00:25:27
something that you would be able to use as like a natural trellis
00:25:31
like the corn in the three Sisters method.
00:25:33
But unfortunately, most crops are not going to be able to
00:25:36
handle the chemical signals or the chemicals that are being
00:25:40
released from those roots. And if they are something that
00:25:44
could handle those allelopathic properties, the other way a
00:25:49
plant could be allelopathic, meaning it is preventing the
00:25:52
growth of things near it is to be basically a nutrient hog.
00:25:56
Sunflower is a very demanding plant and it can usually out
00:26:00
compete anything that it is planted with.
00:26:04
So sunflowers have very deep taproots.
00:26:08
I did a whole episode on sunflowers and their ability to
00:26:11
be able to. I guess it wasn't a whole
00:26:13
episode specific to sunflowers, but it was talking about phyto
00:26:16
remediation, which is the ability to be able to draw
00:26:19
toxins and other contaminants out of the soil.
00:26:23
Sunflowers are fantastic for that and if they have that
00:26:26
ability then you know they have a very, very strong root system.
00:26:31
So they are going to out compete just about anything.
00:26:33
The only thing that I have really seen them not be able to
00:26:36
handle at least in my area is a heavy growth of hemlock plant.
00:26:43
Like we have hemlock out here that is just invasive and goes
00:26:46
crazy. And I had tried planting
00:26:49
sunflowers to kind of out compete the hemlock and the
00:26:52
hemlock just it takes over every time.
00:26:54
So that's something that we have dealt with.
00:26:56
But sunflower great for suppressing weeds, especially
00:26:59
annual weeds, but you you may not want to plant any actual
00:27:02
harvestable crops anywhere near the base of them.
00:27:05
Now, sometimes a plant that we plant intending for it to help
00:27:12
can actually do the opposite. I'm all about experimenting with
00:27:17
companion plants to see what works and what doesn't work in
00:27:20
your garden in your experience. Again, we don't always have to
00:27:24
rely on these science research studies, et cetera, to show us
00:27:29
what works in our own garden. I just don't like to spread that
00:27:33
information to people once I see something works for me because
00:27:36
it may not work for somebody else if I just have anecdotal
00:27:39
information, right? But there are, you know, certain
00:27:42
cases where we know something doesn't work for very specific
00:27:46
reasons. For example, dill.
00:27:47
Dill attracts swallowtail caterpillars, which you know
00:27:52
actually it attacks this that tracks the butterfly and they
00:27:55
like to lay their eggs in the dill.
00:27:57
This also is in parsley as well, but dill specifically, and dill
00:28:03
also attracts aphids so you probably don't want to be
00:28:07
planting those near your tomatoes because you're
00:28:09
encouraging those caterpillars and you're encouraging aphids to
00:28:13
be in your tomatoes. Mature dill can also suppress
00:28:16
tomato growth first via that allelopathy early on.
00:28:20
So you know the early plants aren't so bad, but once they
00:28:23
start to go to flour then the dill can cause a problem.
00:28:27
So it's not usually a good idea to plant dill near your
00:28:30
tomatoes. Same thing goes with sunflowers.
00:28:34
Again, anywhere near beans. So, you know, I will plant
00:28:39
sunflowers along end rows in my garden.
00:28:42
It's usually the one thing that I don't plant in amongst
00:28:44
everything else. But if I'm going to plant beans,
00:28:47
they're going to be at the opposite end of that garden area
00:28:50
because sunflowers can actually attract stink bugs and they can
00:28:53
harbor seed maggots. And this is not something that
00:28:55
we want in our beans because beans are very susceptible to
00:28:57
the damage from those. They're great for pollinators,
00:28:59
the sunflowers are, but you just want to make sure that you're
00:29:02
monitoring them closely near any of those vulnerable crops.
00:29:06
Another one is fennel. Fennel also has allelopathic
00:29:10
compounds and it can inhibit the growth of a lot of vegetables,
00:29:14
most of them actually. So if you are growing fennel,
00:29:18
you likely want to plant it by itself.
00:29:21
And it's a great plant that you can put in a separate pollinator
00:29:25
bed and because it does again, attracts those things like
00:29:28
swallowtail butterflies. And so if you are growing fennel
00:29:31
as your crop to eat, then you want to keep it away from the
00:29:35
rest of your crops that it doesn't actually inhibit the
00:29:37
growth of the rest of your garden.
00:29:40
OK, so there are a few more plants that we may not want to
00:29:44
plant together just you know based on olelapathy or even just
00:29:50
direct competition. The first one is planting onions
00:29:54
or garlic in an amongst beans. So one of the things that we
00:29:58
get, one of the benefits that we get from planting beans or
00:30:01
anything else in the Allium or in the legume family, sorry, in
00:30:05
the legume family, is that beans and other legumes add nitrogen
00:30:10
to the soil through a symbiotic relationship with rhizobium
00:30:14
bacteria. These these bacteria form
00:30:18
nodules on the bean roots, so they convert atmospheric
00:30:23
nitrogen into a form that the plant can use through those
00:30:27
nodules. When the plant dies or when we
00:30:31
cut it down, we leave that root system in the ground, which
00:30:34
means those nodules are still in the soil.
00:30:37
And then as they decompose, they release that fixed nitrogen back
00:30:41
out into the soil. And that of course, helps enrich
00:30:44
the soil for future crops. If we plant onions or garlic,
00:30:49
any of our alliums next to our beans or near our legumes, it's
00:30:55
a bad idea because alliums release sulfur compounds and
00:31:00
Allison, which is an antibacterial compound.
00:31:03
And those compounds can actually kill off the beneficial nitrogen
00:31:08
fixing bacteria that are doing that job for us.
00:31:11
That's those are the bacteria that the legumes need for that
00:31:15
nitrogen fixing. So not only is that going to
00:31:18
affect the plants ability, the bean plants ability to be able
00:31:22
to kind of store up that nitrogen for us and give us
00:31:24
those benefits, but it actually may interfere with the bean
00:31:28
plants growth itself. So we want to avoid planting
00:31:32
onions or garlic in and around near our beans.
00:31:35
Another one would be carrots and dill or parsnip.
00:31:38
These are all in the APACA family and so they can cross
00:31:42
attract carrot flies and also attract the same diseases.
00:31:46
So we don't want to group them together.
00:31:50
The same thing goes basically for other plant families.
00:31:52
So nasturtiums, for example, nasturtiums will repel a lot of
00:31:56
different pests, but nasturtiums are in the brassica family.
00:32:00
And so it would be probably a bad idea to plant nasturtiums in
00:32:04
and amongst all of your brassicas because they're not
00:32:07
going to be very effective at the pests that we're worried
00:32:10
about in our brassicas, like the cabbage moths or other pests,
00:32:12
because the phytochemicals are all the same.
00:32:15
So This is why we generally don't want to plant things in
00:32:19
the same family all together. Same thing goes with like
00:32:22
potatoes and tomatoes. They're both in the nightshade
00:32:25
family, so they are both susceptible to the same fungal
00:32:28
and bacterial diseases, especially blight.
00:32:31
So we want to separate them to reduce that risk.
00:32:35
Does this mean that I'm not planting my brassicas all like
00:32:38
near each other? No, I'm still planting them in
00:32:42
beds that are close to each other because again, we talk
00:32:44
about this all the time. We're not farming on 1000 acres
00:32:47
here, right? And I mean, even I have more
00:32:50
room to plant than a lot of other people do.
00:32:52
But if you're gardening in your backyard, you only have a
00:32:55
limited amount of space. So you're obviously going to
00:32:57
have to be planting some of these plants close to each
00:32:59
other, right? So it's just important to,
00:33:02
again, use that companion planting to mix up all the
00:33:05
species. Tomatoes and corn, these are
00:33:08
both really heavy feeders and they're going to compete for
00:33:10
nutrients a lot of time. Plus corn can host the the corn
00:33:16
earworm, which is also known as a tomato fruit worm.
00:33:19
So that also targets tomatoes. We don't want those pests coming
00:33:24
in and landing on one and also being able to feed on the other.
00:33:27
So those can be, you know, both of the plants weak and it opens
00:33:30
them up to different pests and diseases.
00:33:32
So we don't want to plant those together either In terms of
00:33:36
companion planting with strategy, right?
00:33:39
This is where intercropping or interplanting comes into play.
00:33:43
We're going to talk next week about the strategies like really
00:33:47
dive deep into the kind of systematic version or way that
00:33:52
we can companion plant through intercropping.
00:33:55
It's based on timing, it's based on spacing, it's based on plant
00:33:59
architecture, all of these different things.
00:34:00
But some of the ones, you know, just here briefly that we can
00:34:03
touch on that are really good examples are things like what we
00:34:06
already talked about the three sisters, right, corn, beans and
00:34:09
squash. The beans fix the nitrogen the
00:34:12
corn provides support the squash suppresses the weeds.
00:34:15
And you can also deter like raccoons and stuff from getting
00:34:19
into your corn because the if you're using the squashes that
00:34:23
have like the spiky stems on them, that can actually help,
00:34:26
you know, keep those buggers from crawling in there and
00:34:28
trying to climb up the corn and and pull the corn down.
00:34:30
So lots of different benefits to each other when they're being
00:34:34
planted together, planting fast growing crops with slow growing
00:34:39
ones. So radishes or lettuce being
00:34:42
planted in between longer maturing crops like the broccoli
00:34:45
or your Peppers, not only is maximizing space, it's also
00:34:49
reducing that weed pressure. So those are good companions
00:34:52
together. But again, when we're talking
00:34:54
about deterring pests, we're mixing up those chemical signals
00:34:57
by planting multiple plant families together.
00:35:01
So that is deterring the pests because they can't find their
00:35:04
preferred host nearly as easily, especially, again, appropriate,
00:35:09
inappropriate landings. They land on a radish and go,
00:35:11
oop, that's not what I wanted. I want to land on the carrot and
00:35:14
then they might land on the carrot and then they land again
00:35:16
and oops, back on a radish again.
00:35:17
Like it's it it resets that whole cycle.
00:35:19
So the more things that we can plant together that are not in
00:35:22
the same plant family, the better off we are.
00:35:26
This kind of inter planting, you know, rows of of non host crops
00:35:31
not only visually confuses the pest, but it also, you know, can
00:35:37
confuse them in terms of like the texture and the landing on
00:35:39
them, right? So alternating rows of onions
00:35:41
and carrots that can mask each of those crops from their
00:35:43
respective pests like onion maggots and the carrot rust
00:35:46
flies, et cetera. This is why when I'm planting my
00:35:49
brassicas again, they are being planted near each other.
00:35:52
I might have one full bed that has all, you know, broccoli in
00:35:56
it. That bed right next to it may
00:35:58
also have cabbage in it. And then the one right next to
00:36:01
that might have cauliflower in it.
00:36:03
But they're not by themselves. They are not growing by
00:36:06
themselves ever in those beds. So even though those all attract
00:36:11
the same pests, I am inter planting those onions and those
00:36:16
lettuces and the the Elysium in and amongst them.
00:36:20
So it is still confusing those pests, right?
00:36:23
That is how you kind of get around the space issue when it
00:36:26
comes to growing your crops. If you can inter plant them and
00:36:31
confuse those pests, that's going to help.
00:36:34
To be most effective, we want to choose crops that have different
00:36:37
growth rates and that also have different canopy shapes and we
00:36:40
don't want to overcrowd. This is probably the most
00:36:44
difficult part of this and something we're going to kind of
00:36:46
deep dive into next week. Intercropping works best when
00:36:49
you have a plan and you understand the mature size of
00:36:55
these plants and how they're going to affect each other when
00:37:00
they are all at maturity, whether or not they've already
00:37:02
been pulled or not and that sort of thing.
00:37:04
So we'll go into that a little bit more next week.
00:37:09
Companion planting absolutely works, right, whether or not
00:37:15
we're using it in terms of, you know, increasing our soil health
00:37:19
or protecting our, our, our soil or keeping weeds at Bay or in
00:37:25
terms of pest management. But it works best as part of an
00:37:29
integrated pest management strategy.
00:37:32
I will link to the IPM episode that I did earlier in the
00:37:36
season. But this means prioritizing
00:37:39
plant health and soil health, right?
00:37:40
Because again, our healthy plants and our healthy soil are
00:37:43
going to be much better at resisting those pests and being
00:37:48
able to bounce back once they are predated on and on
00:37:51
monitoring for that pest presence and keeping track of
00:37:55
those lifestyles, life cycles so that we know when and how those
00:37:59
pests are operating. And then combining all of this
00:38:03
companion planting with using physical barriers and natural
00:38:06
predators when appropriate. Doing your homework on which
00:38:11
companions actually have evidence behind them is a really
00:38:15
good place to start. And is also going to sort of
00:38:19
weed out which ones might just be garden folklore.
00:38:24
A lot of plants do express insecticidal traits.
00:38:27
The key is to use them for your benefit and use them on plants
00:38:33
that are very dissimilar and that way they produce different
00:38:36
phytochemicals. So again that you know that
00:38:40
reference to the nasturtiums, they do repel pests, but they
00:38:43
are in the Brassica family. So maybe don't use them to try
00:38:46
to deter pests from others in that family.
00:38:49
Put them in with something else like maybe your squash plants.
00:38:53
And if you have, you know, or, or just use them as a trap crop,
00:38:57
if you have tried a companion planting combo that works for
00:39:01
you, there is no reason not to continue it if you know it's
00:39:05
working. And you can go ahead and share
00:39:07
that, you know, let me know. I would love to, you know, hear
00:39:10
some real world examples of things that have worked for you.
00:39:14
If you have tried a companion planting that totally flopped
00:39:18
and maybe you didn't realize why it flopped until later on or
00:39:22
even just now listening to this episode and realizing, oh,
00:39:27
nasturtiums attract aphids and I was trying to get rid of aphids
00:39:30
but I put them in and they were, oh, now I understand.
00:39:33
Go ahead and let me know that too.
00:39:35
I would love to hear about it again.
00:39:37
If I hear a bunch of real world examples from people, I am super
00:39:39
happy to, you know, update everybody in a future episode to
00:39:42
let them know like, hey, this has worked for some people,
00:39:45
maybe it'll work for you. Just remember, when you are
00:39:48
dealing with anecdotal companion plantings, what works for one
00:39:52
person may not work for another one.
00:39:54
So do not rely on any of these companion planting suggestions
00:39:59
as your sole way to keep insect pests at Bay in your garden.
00:40:04
Make sure it's part of an integrated plan and that you
00:40:07
have more than one way to keep away those pests.
00:40:10
Until next time, my gardening friends, keep on cultivating
00:40:12
that dream garden and we'll talk with you soon.