Canary plants

This is a topic that I know very little about, so by starting this thread I'm hoping a collection of permie knowledge will ensue.  Google has been little help.

The idea of a "canary plant" is really a rather simple one.  Certain plants will show things like mineral deficiencies, fungal issues, and pest problems sooner than others.  The concept comes, of course, from the "canary in the coal mine."  Whether these "canary plants" are grown intentionally for this purpose or only incidentally, their function is the same.

A couple (vague) examples:

1.  I don't even recall where I heard this, but I think it was a podcast for something or other.  No matter.  A vineyard makes a practice of putting a rose bush at one end of each row of grapes.  There is a fungus or pest or somesuch that attacks the roses before the grapes, which allows the farmers to take action before the entire vineyard is affected.

2.  I'm not sure if this even qualifies, but it seems likely.  Reading some of Wendell Berry's fiction, there was mention of a row of tomatoes planted at the end of a tobacco field.  No explanation was given; it's possibly just a good idea for plant requirements and/or crop rotation, but a "canary plant" usage seems likely as well.

It strikes me that there is overlap with the idea of trap crops, and maybe more.

So what have you got?  What "canary plants" have you used, intentionally or by accident?

When the forsythia are flowering, it's time to plant peas.

When the apples are flowering, it's time to plant the first crop of corn.

Joseph Lofthouse wrote:When the forsythia are flowering, it's time to plant peas.

When the apples are flowering, it's time to plant the first crop of corn.

That's useful information, and incredibly interesting, but a different concept.  There is some overlap, of course.  The term for this practice slips my mind, but I believe there's a thread devoted to the topic.

What I'm more interested in here is plants that indicate particularly early when something is amiss, giving one an opportunity to take action before it's too late.

Some plants like hydrangea produce different coloured flowers depending on the minerals and ph of the soil.

There are indicator plants. Certain plants that grow will tell you particular soil conditions that are prevalent in that area. You might try searching that and see where it leads.

Roy Hinkley wrote:There are indicator plants. Certain plants that grow will tell you particular soil conditions that are prevalent in that area. You might try searching that and see where it leads.

If you find any, please post them here.  It would be great to make this thread a one stop resource for future readers.  

Another one that just came to mind.  I believe I read this in one of Frank Tozer's gardening books (they're really useful, if far from glitzy-- check them out!).

Sunflowers supposedly will show effects of water stress sooner than other plants.  So if it's been dry and your sunflowers start to droop, it's time to water the garden (or at least the plants that don't handle drought).

Try this from the Old Farmers Almanac
Weeds as Indicator plants
https://www.almanac.com/blog/gardening/garden-journal/weeds-indicator-plants

There is a book called Test Your Soil With Plants second edition by John Beeby.  This book might be of use.

Talking books I remember once looking at a book in the library called "weeds and what they tell" quick internet search found a newer edition "weeds and what they tell us" and another book "when weeds talk". Regarding Joseph's plant phenology comment I like that I can tell my corn planting time by when my white oak leafs out. We need a thread for that as well.

When I have done some rangeland vegetation plot work I learned that different named soil types usually correspond to certain plant communities. Look up your soil type online using the if you are in the United States use NRCS's free online tools to look up your soil type and you may be able to find a plant list that goes with.

William Schlegel wrote:Talking books I remember once looking at a book in the library called "weeds and what they tell" quick internet search found a newer edition "weeds and what they tell us" and another book "when weeds talk".

Another book on soil health indictors for those with thin wallets. This book is available via download here at no charge. http://soilandhealth.org/copyrighted-book/weeds-guardians-of-the-soil/

Weeds: Guardians of the Soil

Cocannouer, Joseph A.
Original publication date: 1950
Original publisher: Old Greenwich, Connecticut: The Devin-Adair Company
Publication status: Out of print
The weed species that thrive at any location reveal a great deal about the soil they are growing in. This book has long been admired by holistic gardeners and homesteaders.

There is a lot of truth in different "weeds" or undesirable plants, growing about and what they say about the soil. Some prefer very acidic soils, like pH 5.5 or less, and identifying those can tell you that the soil is rather acidic for growing food crops (except for some plants like blueberries). I wish I knew more about the stories different plants tell about soil, but I haven't gotten there yet. The one I do recall off the top of my head is dandelion, it prefers to grow in soils that we would consider deficient in calcium, which is also an indicator of acidic soils.

A vineyard makes a practice of putting a rose bush at one end of each row of grapes.

In one of his recorded PDC lectures Bill says a woman he met on a vineyard in Italy told him that 'the rose is the doctor of the grape'. Maybe this is what she meant? I've always thought it was more along the lines of a symbiotic relationship.

It seems like there are a few ideas here though:

- Plants that help to indicate what action we should take with other plants
- Plants whose germination conditions can teach us something about the site
- Plants with particular weaknesses that can be used to indicate something.

It seems like the third one is the idea behind 'canary plants', is that right?

Sunflowers supposedly will show effects of water stress sooner than other plants.

I've found the same to be true of basil- it will start to droop before anything else, and also shows signs of heat stress before most anything else in the garden.

Has anyone read that John Beeby book? Seems like that's spot on for this.

Cody DeBaun wrote:In one of his recorded PDC lectures Bill says a woman he met on a vineyard in Italy told him that 'the rose is the doctor of the grape'. Maybe this is what she meant? I've always thought it was more along the lines of a symbiotic relationship.

It could very well be a symbiotic relationship, but in this particular case the growers were using the roses as a sort of early warning system for a particular (bacterial? fungal? insect?) pest.  By placing the rose bushes at the ends of the rows, they could check the status of the pest without having to go up and down the rows.

I suspect that along with their "canary" function, the roses served as a sort of (at least temporary) trap crop.  There's overlap there, too, in concept.

I'll throw out another one.  We have lots of multiflora rose.  I hate the stuff.  (It brings to mind the Biblical curse about "thorns and thistles," and makes it very real!). But over the years I've found that Japanese beetles will start attacking multiflora rose (and other roses, too, I'd assume) before nearly anything else.  So when I notice the Japanese beetles on the rose bushes, it's time to keep an eye on the garden crops that they seem to particularly enjoy, because they'll be moving to them next.

It seems like there are a few ideas here though:

- Plants that help to indicate what action we should take with other plants
- Plants whose germination conditions can teach us something about the site
- Plants with particular weaknesses that can be used to indicate something.

It seems like the third one is the idea behind 'canary plants', is that right?

Sounds about right, and of course there is overlap on multiple levels.

Phenology (the second point on your list, examples of which Joseph gave earlier) certainly shows relationships between plants, but not in the negative way that I think we're discussing here.

I think the idea of "indicator plants" (which the books mentioned previously are concerned with) is very similar, if subtly different.

Indicator plants, I'd say, address chronic issues like soil mineral content, fertility, moisture level, etc.  Canary plants, by contrast, address acute issues, and I think that is perhaps the main difference.  So while an indicator plant might show you generally that your soil is low in calcium, say, you'll probably still be able to grow a lot of stuff; a canary plant might, on the other hand, show you that, regardless of overall condition, something is amiss with a particular crop or crop family that needs to be taken care of soon, before you lose the crop.

I observed that wood carving insects prefer red plum trees (Prunus cerasifera I guess- red plums with dark red foliage) above all. I don't know which species they are exactly but definitely includes carpenter ants and termites. Tree reacts with a sticky substance, forcing the dwellers to move on to other fruit trees. Similar to the poor canary, it is sacrificed. Feeding the fish with logs full with insects is one option, burning is another. Red plums are always the first tree targeted in my garden. It might be a candidate for canary plants, maybe?

s. ayalp wrote:
Feeding the fish with logs full with insects is one option...

I'd like to know more about how to do that---throw it in the pond? hang it over the pond? Or...?

Nasturtium, besides being a tasty treat, are very vulnerable to frost.  So if your not sure how cold it got last night they will wilt before the tomatos or squash.  A forwarning of things to come.

Wes Hunter wrote:Sunflowers supposedly will show effects of water stress sooner than other plants.  So if it's been dry and your sunflowers start to droop, it's time to water the garden (or at least the plants that don't handle drought).

I don't have that experience with sunflowers, here.

I actually use comfrey for this.  Even though comfrey is deep rooted, it needs more water than most things I grow, so it wilts before the other things die.  It is dry enough here that the (bocking 14) comfrey doesn't spread too much.

I love the idea about the weeds, but I read lots of conflicting advice about it on the Internet.  Does anyone have actual experience with any of these books listed here?

Wes Hunter wrote:

Joseph Lofthouse wrote:When the forsythia are flowering, it's time to plant peas.

When the apples are flowering, it's time to plant the first crop of corn.

That's useful information, and incredibly interesting, but a different concept.  There is some overlap, of course.  The term for this practice slips my mind, but I believe there's a thread devoted to the topic.

What I'm more interested in here is plants that indicate particularly early when something is amiss, giving one an opportunity to take action before it's too late.

A very interesting thread, but rather than "sacrificing" one plant, which gives you one indication about one other valuable species, we might get a better understanding of our soil by testing it. This testing would be a lot more complete and help us across all species.
The "sacrificed" plant idea brings up another problem which I did not see expressed in this thread: Just like the Japanese beetles will flock to a trap, and from there munch on my apples and grapes, isn't it possible that the plant that you place nearby as a warning system will actually *attract* pests to the general area?
There is symbiosis between plants, which is slightly different in its concept if you look at "companion planting", and there are some plants that actually prevent other plants from growing near [Black walnuts are notorious for not allowing other plants nearby, and pussytoes in your lawn will spread if not removed as they are alleopathic too].
The idea of a canary plant is interesting, certainly but it touches on so many possible permutations as to not being really "workable", I think.

I've often used Peace Lily (Spathiphyllum) as a "canary plant" in my house.  These plants are terrific house plants because they are good at removing VOCs from the air, they are also very dramatic when they lack water.  They droop in a very obvious way!  So, when I see my Peace Lily pouting, I know it's time to water all the houseplants.

Hi Cat,
I just throw them in the pool, logs branches and etc. Koi eat whatever sinks, remaining is devoured by insectivorous fish (we call it fresh water-silver fish - I don't have guppies). Logs remain in the water for about 10-15 days because I am lazy and they start to sink afterwards.

s. ayalp
I just throw them in the pool, logs branches and etc. Koi eat whatever sinks, remaining is devoured by insectivorous fish (we call it fresh water-silver fish - I don't have guppies). Logs remain in the water for about 10-15 days because I am lazy and they start to sink afterwards.

Pretty much what I was imagining--thanks!

Cécile Stelzer Johnson wrote:A very interesting thread, but rather than "sacrificing" one plant, which gives you one indication about one other valuable species, we might get a better understanding of our soil by testing it. This testing would be a lot more complete and help us across all species.

When it comes to soil nutrients, this is probably true.  But the canary plant concept might still be useful for those who cannot afford regular soil testing (and good soil tests aren't cheap), or for whom testing is impractical for one reason or another.  And it's not necessarily a matter of "sacrificing" anything, but of noting relationships.  It's quite possible that, in a given situation, the canary plant is a weed growing in an out of the way place.

The "sacrificed" plant idea brings up another problem which I did not see expressed in this thread: Just like the Japanese beetles will flock to a trap, and from there munch on my apples and grapes, isn't it possible that the plant that you place nearby as a warning system will actually *attract* pests to the general area?

This, perhaps, is where the canary analogy breaks down (as all analogies must break down at some point).  The canary was introduced to the coal mine for the singular purpose of acting as a warning system.  In the garden, however, canary plants might be included for a whole host of reasons.  I can't imagine someone planting something for the sole purpose of indicating when a certain pest is around, and thereby risking attracting that pest.  So the canary plant is included because it is wanted for some other reason(s), and only incidentally serves as a canary.

In my example of multiflora rose, it's just there.  All over our 25 acres.  I knock it back in places, but it will probably always be here.  And that's not a bad thing, as it has a number of pluses to offset the minuses.  But in this case, the Japanese beetles, which are also going to be here regardless, always find their way to the multiflora rose first.  When I start to notice them, that's my cue to start checking on other things that they like as well that are more valuable.  It might be that I wouldn't even check the pole beans for a couple weeks, for example, and might lose the whole crop if it weren't for this particular early warning system.  And if it weren't the multiflora rose, it'd be the grape vines they were after, or the apple tree, or the sour cherries, or the corn silks...

When i was a geology student in the early 90's i had to do a geological map of the Givet Region (northern France on the Meuse River). At the time is was told that ivy (https://en.wikipedia.org/wiki/Hedera_helix) grows almost anywhere. However if it grows high into trees it is an indicator for Calcium or lime into the ground.

There seems to be some truth to that. At the time i used the idea to make my geological map. I checked it whenever i could and it seems true. However in a geological context you might be trown of track by the fact that lime is present in many building materials. So any place near humans settlements, ruins, whatever may nave a high Ca-level due to man's actions.

Nettles are an indicator of high nitratelevels.

There are also metallophytes which were used to spot heavy metal deposits. No english wiki on this.
https://nl.wikipedia.org/wiki/Zinkflora
https://de.wikipedia.org/wiki/Galmeivegetation
https://en.wikipedia.org/wiki/Metallophyte

Good reading.