Gardening science versus tradition

Discussion in 'Plants: Science and Cultivation' started by Margot, Jul 26, 2020.

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  1. Sulev

    Sulev Active Member

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    I am pretty sure, that this is not what "In extreme cases, REPLACE the ENTIRE PLANTING SITE with topsoil" means.
    But as you start to alter meanings of simple sentences in your native language, that is not my native language, I see no point to argue with you.
     
    Last edited: Jul 31, 2020
  2. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    OK, y'all, stick to the topic. I participate in FB to prevent the demise of present day music and musicians. And to see the notices of the garden's blog postings.
     
  3. Sulev

    Sulev Active Member

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    My intent is still to improve drainage, according to the myth.
    If you decrease the amount of soil below the proper amount, that corresponds to the plant size, then your results are biased, because you don't know if any possible adverse effect is caused by the added drainage or smaller than needed amount of soil.
     
  4. Sulev

    Sulev Active Member

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    This is exactly amending a planting hole, what is myth-busted by Dr Chalker-Scott. She recommends to backfill with pure original soil only. Dr Chalker-Scott does not rise the planting hole size issue. Her myth-busting conclusions are similar for any size. That's one of the reasons, why I called this myth-busting shallow and narrow minded.
     
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  5. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    The point of the article is that drainage is in fact not improved by adding the layer but has the opposite effect of pushing up the perched water table within the container. I suppose that would be good if the intent is to grow aquatic plants. Perhaps the disagreement results from a difference in perspective. Most people would assume a proper sized container has been selected in relation to the size of the plant. However it seems you're taking the opposite tack in assuming a mismatch in container and plant to begin with. Are you then not the one who is biased?
     
  6. Sulev

    Sulev Active Member

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    And I am sure, that this myth-buster's conclusion is wrong, because the experiment was biased. I am sure, that important is the amount of the soil, and container must be choosen according what to put into the container, including proper amount of soil and the drainage layer, if needed.
    I suppose that adding drainage has point for plants, that don't tolerate longtime wetting of roots (like citruses, figs etc), have pretty large container, with excess water collector under it. If to add proper drainage layer, that rises bottom of the soil out of possible excess water pond, then the drainage does what it is meant to do. Provided, that there is proper amount of soil on top of the drainage layer.
     
    Last edited: Jul 31, 2020
  7. Sulev

    Sulev Active Member

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    I quote here my year old posting from another thread (Elephant ears-can they be moved from ground to pot?):
     
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  8. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    I believe I have already addressed this. The layer is needed only if an overly tall container is chosen. Why not buy the proper sized container to begin with?
    Are you saying the layer is needed in case the container is allowed to sit in a 'pond' of water? Why create the pool of water in the first place?

    Again I submit the bias in not in the research. Here's another article on the subject, with findings from multiple sources, which explains matters much better than I can: Should You Put Gravel or Rocks at the Bottom of Plant Pots for Drainage?
     
  9. Sulev

    Sulev Active Member

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    @Junglekeeper - the myth is: "The Myth of Drainage Material in Container Plantings: "ADD a layer of gravel or other coarse material in the bottom of containers to improve drainage"" not "Replace (part of) the soil with a drainage material". A scientist should be precise in definitions and follow that experiment corresponds to definitions.
     
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  10. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    Are you then suggesting people should intentionally buy tall containers just to accommodate a layers of rocks at the bottom?
     
  11. Sulev

    Sulev Active Member

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    Oversized containers and adjusting them by adding certain materials below the soil are totally another topic.

    Drainage is needed because it is pretty hard and troublesome to remove excess water from the collector in case the container is large and heavy or if the plant is especially fragile and does not tolerate moving. Plant saucers for collecting excess water are used widely. Primarily for keeping excess water from dripping or pouring into places where it should not reach.
     
  12. Sulev

    Sulev Active Member

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    If the drainage layer is useful for the plant, then yes, I suggest then to select container size, that fits both proper amount of soil and the drainage layer. I consider any other option as a strange solution to the problem.

    It seems to me, that the myth-buster and these scientists she cites forget completely, what is the purpose of the drainage layer, and have ignored this principe when designing their experiments.
     
    Last edited: Jul 31, 2020
  13. Sulev

    Sulev Active Member

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    I suggest to the myth-buster to experiment with different height of the drainage layer with constant volume of high organic content soil (that has high capillary rise of water) on top of it, and different watering frequency (with constant water volume) of citrus plants planted into these containers, over plant saucers for collecting excess water, no manual removal of the excess water from the saucers. Citruses like high organic content of the soil, like constantly moist soil, but don't like soggy soil, and should show any possible effects of drainage layer.
    The control is, of course, the same volume of the soil without the drainage layer.
     
  14. Margot

    Margot Contributor

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    @Sulev: I had some hopes in a few recent posts, when you started to refer to Dr. Linda Chalker-Scott by her proper name, rather than using pejorative terms like 'myth-busting Linda' or calling her shallow, narrowminded or an entertainer, that you would be more moderate in your comments about her personally. Whether you agree with her or not, she deserves to be treated with respect, having devoted decades of her career helping thousands of home gardeners create more successful gardens. She is highly regarded among her peers.

    Discussion is different from argument, wouldn't you agree? As this discussion increasingly devolves into argument, I weary of the adversarial tone and will now recuse myself from further comment. Thank you for your input.
     
  15. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    I'm not sure what that would achieve but for the purpose of this experiment, let's assume the container is a cylinder, tall enough to accommodate the contents of each individual scenario. Since the only variable parameter is the height of the rock layer, the perched water table will be the of same height and location relative to the soil layer in all scenarios. The watering frequency is irrelevant.

    Aren't you just creating scenarios to further your argument? While it's true there are some exceptions, in general it is better to not have the layer in place. The science behind this is clear. It's up to the reader to choose how to apply that knowledge.
     
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  16. Sulev

    Sulev Active Member

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    The perched water table is irrelevant, because if to use the proper volume of soil which is suitable/recommended for the plant, then the perched water table stays safe for the plant. Anyways, as the soil volume and shape stays the same between the drained plot and the control, any difference in results can't be caused by differences in perched water table (a scientist should eliminate other factors that may influence the factor under the scope). Difference in results may come from the excess water, that is wicked up from the plant saucer, and that is the issue, what drainage layer is meant for. See the picture above (from the post, where I quote my year old message, I think the picture is self explanatory).

    Watering frequency is relevant as you must deliberately create unfavourable (too moist) conditions to see if drainage works or not. Drainage is meant for cases, where plant owner accidentally or from poor habit/poor knowledge waters too much/too frequently. Drainage is not needed if plant owner can constantly keep optimal moisture level in the soil. Drainage won't help if you constantly pour huge amount of water to the container. It works in the specific range of over watering. To hit the range, a scientist must use different watering frequences in several steps from optimal watering to strong over watering. Only then it is possible to find out what is the range of benefit from the drainage layer.

    My suggested experiment is designed to show possible benefit from the drainage layer. A scientist must not design her experimemt NOT to show benefit, if she wants to prove the absence of the benefit. On the contrary, to prove the absence, the test must be designed maximally favour the appearance of the benefit. Only if the scientist does all what is possible to encourage the benefit, but the results still show no benefit, she may say, that myth is busted. That's the way science works!

    I believe that traditional container shape - narrower from the downside, wider from the upperside, is very wise and reduces the amount of water staying in the perched water table (the area is smaller, the height is the same, compared with cilindrical shape). When trying to bust traditions, stick to the traditional conical shape! I think that old traditions have often big amount of wisdom of ancestors included, therefore I consider busting traditional methods with blind hate insulting towards our ancestors. It is possible that people use old traditions incorrectly (because of their ignorance), therefore scientist must teach when and where to apply certain traditions and where not, instead of busting these traditions.
     
    Last edited: Aug 1, 2020
  17. Sulev

    Sulev Active Member

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    This linked site seems completely to forgot plant saucers, that collect excess water and are widely used for growing indoor plants.
    There is no need for drainage layer if the excess water can freely drain to the ground. But that is not the case for indoor plants! People don't like if the excess water pours freely to their windowsill, furniture or floor.
    So the bias is there!

    Let's see, what for the drainage layer is actually recommended in these "myths". From the The Complete Guide To Planting Houseplants In Pots & Planters
    "Cache Pot & Pot Liner
    If taking the plant in and out of the decorative pot to water or empty excess water from a saucer is not your thing. You can add a liner to the decorative pot and some drainage material..."
     
    Last edited: Aug 1, 2020
  18. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    In spite of your numerous posts I'm still not sure exactly what it is you are proposing. As far as I can tell, you are suggesting in a very roundabout way that a drainage layer (more accurately a capillary break) should be installed within the container in case excess water should accumulate in the saucer. While it may have such a purpose it does not alter the fact the addition of the layer pushes up the perched water table and in order to not end up with less useable soil, a taller container must be used. Once again, the layer does not improve drainage of the soil but rather serves as a capillary break. That aside, it is the norm in the majority of cases for excess water collected in the saucer to be discarded. Therefore there is no need for such a layer under normal circumstances.

    The usage put forward in the link is that of an absorbent layer whose purpose is to soak up excess water that has drained from the container. Furthermore it exists outside of the container and therefore does not affect its internal characteristics.

    As you are convinced that the studies on the matter amount to poor science I suggest you put forward your assertions to one or more of the research groups named in the document previously referenced for their feedback. By the way, have you conducted controlled experiments that have been peer-reviewed in the scientific community that support your views?
     
    Last edited: Aug 2, 2020
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  19. Sulev

    Sulev Active Member

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    No, you got me wrong. I am not proposing planting methods. I am proposing to myth busters how to correctly scientifically prove absence of effects that they deny.
    Because I see, that their experiments for myth busting are biased, they don't test the range, where the effect they deny is most likely present, and they make too wild generalizations and conclusions. They generally don't follow the Scientific method - Wikipedia properly and their myth busting should therefore not be called as a science.

    The drainage layer in containers is not obligatory. The question is if it has any benefit in case of growing specific houseplants, that are sensitive to over watering, when the plant owner is not the most experienced to follow optimal watering regime and is a bit lazy/sloppy to use watering methods that avoid excess water staying on the plant saucer/excess water collector and wicking back to the soil from there, causing long term water logging and damage to the roots. The drainage layer does its job to break the capillary raise of water regardless its location on the bottom of the container or below the container. I have known the effect from childhood as my mother used to fill the bottom of cactus containers with a coarce white sand to break water wicking from the saucer (because we, children, got sometimes an idea, that our plants need watering, and succulents don't like at all if several persons are irregularily watering them).

    I am not a scientist, but I have learned the scientific method during my 6 years of studying in the Estonian Agricultural University (now the Estonian University of Life Sciences), after 4 years of studies in the Luua Forestry Technical School. Finished both schools cum laude. And I have several dozens of years of forestry and agricultural practise, including planting thousands of forest trees, but also growing fruit trees and berry bushes ontop of a white sands, planted into amended planting holes. I don't use a drainage layer in containers as I don't grow much house plants, most of my container plants are very young and stay in containers only few months before replanting. And I consider myself careful enough not to overwater too often (but I have still lost number of citruses, figs and other plants due to overwatering).
     
    Last edited: Aug 2, 2020
  20. Sulev

    Sulev Active Member

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    No, adding the drainage layer does not push up the perched water table, unless you don't think, that positioning the container to the higer shelf also pushes up the perched water table.
    Replacing lower part of the soil with a drainage layer pushes up the perched water table in the remaining soil.

    The perched water table is another topic, irrelevant to what for the drainage layer is recommended to use (to separate the excess water from the soil).
    In the perched water table the amount of water may be much smaller amount than on the excess water collector. Especially if the layer of remaining soil is thin, there can't be much water in the perched water table, and that, what is, can evaporate quicker, because of thin soil layer. The amount of water in perched water table can be adjusted by selecting the soil loam. The soil with a coarser loam and smaller organic content has usually less water in the perched water table. So plant grower can adjust the perched water table in containers according to the plant's needs (by selecting the soil mix, its organic content, thickness of soil layer, shape of the container etc), but the drainage layer is not for adjusting that.

    Don't these myth busters know the essence of the drainage at all? Do you use drainage on fields and sports courts in Canada? The idea of drainage is not to remove perched water table from the soil, it is meant for removing excess water quickly from the soil so that it can't cause long time water logging and will not be wicked back to the upper soil layers.
     
    Last edited: Aug 2, 2020
  21. Sulev

    Sulev Active Member

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    How does it sound: Don't add a drainage layer under the soccer field, as the drainage layer pushes up the perched water table and the soccer field becomes more moist than it was without the drainage?
     
  22. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    But aren't you comparing apples and oranges? The drainage studies are disproving the effectiveness of a layer used in improving drainage within the container while you're advocating its use as a capillary break to prevent a plant from drowning in a pool of excess water that has already drained. You may call it a drainage layer in both cases but they have different intended purposes. As you pointed out, a capillary break has its uses in certain situations but in most cases it would be simpler just to make a practice of emptying the saucer. But if you are going to have a capillary break, aside from aesthetics, why have it inside the container where it will affect soil dynamics? Why not just place the container on top of a tray of pebbles?

    How am I wrong? Refer to the diagram in Should You Put Gravel or Rocks at the Bottom of Plant Pots for Drainage? under the heading "The Effect of Placing Gravel at The Bottom of a Pot on the Perched Water Table". In order to not reduce the amount of usable soil, the original volume of such has to be maintained and in doing so necessitates the use of a taller container than otherwise required.

    I'm not an expert on the design of playing fields so I looked for the answer. It seems the layer works in conjunction with a drainage system below it. Take note of the its effect on the soil above.
    With a container, the excess water will drain into the saucer with or without the layer. There isn't a problem as long as the saucer is emptied when filled.
     
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  23. Tom Hulse

    Tom Hulse Active Member 10 Years

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    My problem with garden mythbusters like LC-S is they often prop up a straw man as a real garden myth when it's just not a real myth. Often it's just a mistake one or a couple authors made, misunderstanding the reasons for very-widely-shared traditional advice. Other times I've seen where she writes a fancy scientific-sounding article full of big unnecessary words to impress the reader, with formal references for the science she cites as proof; but when I go to read her references, they don't support her claim at all. Instead she has extrapolated the very key points based only on her personal opinions. The whole article is actually not worth any more than some random opinionated guy on the internet (like me!) stating their unfounded opinion. A third problem is that she cherry-picks very narrow and limited studies, then puts a group of these narrow studies together and wrongly claims it's an overall "bottom line". For instance look at this piece of ridiculous article on seaweed extracts by Linda Chalker-Scott. Notice she doesn't cite her sources so you can't point out her errors in interpreting and quoting out-of-context! The studies she is referring to were very, very narrow and limited compared to the broad body of scientific work done on seaweed. Most scientific studies on plants are basically done by little more than children with no practical experience in the fields they're studying yet, so they don't know that the question they "proved" was not the relevant question to ask in the first place; resulting in these correct but too narrow and irrelevant studies. Here is a real scientific look at seaweed for gardening in 2009. The facts there are directly polar opposite her narrow and biased hatchet job of a "mythbusting" article:
    She is sooooo wrong on some articles like this that I can't imagine she is being deceitful, it's got to be just plain lazy since anyone can find the facts on Google Scholar in just a few minutes. Yes she has some right things in there, but way too few, and using claims of scientific studies while not citing them. Anyone like this should not be taken seriously at all.
     
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  24. Sulev

    Sulev Active Member

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    No, I am not comparing apples and oranges. Do you know, why roads are raised up with a thick layer of rock rubble and sand? That is a drainage layer, and meant for breaking capillary raise of water, that is drained into the soil under the road.
    Sometimes it is not so easy to empty the tray. House plants can be quite large and containers heavy. And if placed into decorative pot around the container, then the access could be difficult.
    Tray pebbles hide the amount of water from view until they are covered with water. Drainage inside the container will not. So unskillful plant grower can see, when it is last time to stop pouring water (when it already starts to drain onto the saucer), at once, not after it has already filled the saucer.
    Adding a layer will not decrease the amount of soil. Replacing or substituting the soil with a drainage layer would do. A scientist should be precise in definitions.
    Is removing a layer of soil your regular practice if you ADD a layer of mulch or even when you ADD some fertilizer?
    A scientist should identify important factors and causality. If studying the effect of one factor, she must do everything to eliminate or neutralize the effect from other factors, keeping these factors similar for the test and the control. The amount of soil in containers is definitely an important factor for growing containerized plants. Scientist should eliminate its effect when testing other factors by keeping the soil amount constant between the test and the control.
    If adding of a drainage layer often means in practice, that people just substitute some soil with a drainage material, then scientist should point this bad practice, not to blame the drainage layer.
    If the drainage layer pushes up the perched water table in the container, then it pushes the perched water table up in soccer field also.
    The problem is, that it will not drain, if the saucer is not emptied. And that's the case, where drainage comes in use. But that case is out of scope for myth busters. But these "myths" mostly recommend to use the drainage layer in case the plant owner is not so skilled and careful to keep optimal watering regime.
     
    Last edited: Aug 3, 2020 at 1:51 AM
  25. Sulev

    Sulev Active Member

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    Exactly my point. Her works are far from science, as they don't follow the scientific method. Sometimes it seems, that this is the opposite of science, and she is creating myths. And these myths are fallen on a fertile soil, as more and more sites in the Internet cite her pseudo science.
     
    Last edited: Aug 3, 2020 at 1:36 AM
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