Thursday, 3 December 2015

Myths and Legends; Misconceptions in Gardening.

It's all a conspiracy - the world is flat.

I've just bought Charles Dowding's book; "Gardening Myth and misconceptions." published in 2014.  I have read its 91 pages fairly quickly and found it really interesting. 

He, like many other modern commentators, are following an long tradition of challenging gardening misconceptions. 

Ralph Austen's in his 1653 book; "A Treatise of Fruit Trees Showing the Manner of Grafting, Setting, Pruning and Ordering Them"  set out to expose myths during Oliver Cromwell's time. 

He rejected the idea: "To have all stone fruit taste as you shall think good, lay the stones to soak in such liquor as yea should have them taste of."  Together with: "To have red apples put grafts in pike's blood."

Both perfectly reasonable assertions.  (My choice would be Scotch whiskey.)

As are modern misconceptions - put science misconceptions into Utube and you will be very surprised about what ordinary people think about science "facts" that have relatively large amounts of evidence to suggest that they are more or less correct. 

Evolution is rejected even though it is the explanation of hybridisation (Fairchild's mule), plant breeding, plant cloning(taking cuttings), the origin of flowering plants, plant adaptations and interactions with pollinators, plant genetics and grafting.  (Why you can't graft a peach onto an apple. Has God done this just to be awkward?)

Lettuce, believe it or not, does contain protein!  All living things that we know about have proteins.  Proteins are fundamental to life on the Earth.  Don't ask me as a vegetarian where I get my protein from!  I get it from lettuce.   

Let's remember photosynthesis when considering where the mass of a tree comes from.  Yes, those  
Sequoiadendron giganteum are overwhelmingly  just wisps of carbon dioxide gas and drops of water and so are we.  The scraps of other nutrients that plants get from the soil are minisculely insignificant in comparison.  They do not get their mass from the soil.
"General Sherman tree looking up" by Jim Bahn - Sherman Tree
Uploaded by hike395.
 Licensed under CC BY 2.0 via Commons -
That's why General Sherman does not have a gigantic hole around it.  I  know cus I've been there.
I must admit to a vested interest in science misconceptions.  They were my area of research while I was teaching at University and my Master's degree was in the public understanding of science and science communication.  I was researching the misconceptions of children and found that my students - some of which were Masters graduates - seemed to have the same misunderstandings. 

One of the areas I interested in was people's understanding of the phases of the Moon.  This is how we see "daylight" and "night" on the Moon's surface from earth (the planets including the Earth have phases too!).  I have to be careful here because a day is defined as 24 hours on the Earth.   Many people still think that phases of the Moon are bought about by the shadow of the Earth and some children think you can sit on the crescent Moon fishing.  Dowding, although cautious,  seems to suggest a connection between how we see daylight and night on the Moon and the most auspicious time to plant seeds.

Most scientists would say that correlation does not mean cause and effect.  Something that social scientists really need to take on board.  Particularly those in education research.  If its not significant - then it is not significant.  A great deal of evidence is needed to establish  relationships.  As Robert Pavlis  says on his blog, "Garden Myths".  If it is anecdotal then it is anecdotal - not scientific evidence. 

A major misconception - particularly with scientists is that they are dealing with "facts" rather than reasonable consensus based on current evidence.   At the moment we rely on statistics and significance to indicate relationships although how robust this is, can and should be questioned. 

Social scientists in the 1970s and 1980s started to question whether science was as objective as it made out.  It would seem that a great deal of science seemed to have been noticeably distorted by cultural considerations.  This was not done deliberately but as a result of science being embedded in culture. 

You can see this particularly in gardening myths.  What seems to be a "religious" approach to modern compost making probably originated from the Victorian kitchen gardens of the super rich.  There were no scientifically developed seed and cutting composts so they had to develop these composts for themselves.  Each head gardener would have their own recipe and methods.  However, nowadays we can buy reliable growing media from a garden centre without having to go through what seems to be a religious ceremony to produce the same thing from garden waste.  You don't need anything or to do anything special to produce very passable compost.  Just heap it in a pile and leave it for a year.  Now if this is not questioned then it will carry on as it has for 300 years. 

For example the term, "well rotted manure or well rotted compost" is used by Abercrombe's  in the 18th century through Loudon in the 19th century until the television programs of the 21st century.  No one seems to question what "well rotted" means.  However, Dowding does say use year old, friable manure.  I just wonder if it is a year from when it comes out of the animal or one year from when it was delivered to the garden - or whatever.  What is well rotted manure?  I am not really bothered because I put it on the garden as soon as I get it anyway.  Its not doing any good in a pile. 

Which takes us to the "burning of roots" misconception.  While fresh stable manure quickly heats up in a four or five foot pile,  it doesn't do this in a thin layer on the garden - anecdotally.  However, if the manure is nutrient rich then there may be an increase in the concentration of salts in the soil and water will tend to be drawn out of the root giving the impression of "burning. "  But I have never seen this in all the years I have been heavily manuring the allotment.  Thankfully Dowding seems to agree with this.  The Victorian kitchen gardeners used fresh stable manure packed into 3-4 foot stacks to make hot beds and this might have been where this came from.  Also they had so much manure compared to today that they could leave it to rot down for some time before using it. 

Dowding says a little bit about nitrogen depletion by woody material as well.  The Victorian gardeners did use bark chippings called tan, produced from the tanning industry, to make hot beds.  However, they did not use it on the soil probably because they did not need to.  They had so much manure.  Digging in branches and woody stems would have seemed perverse to the outdoor gardeners because it would make digging that much more difficult.  To keep digging up long woody stems would slow the work down and make it hard. 

There is little solid evidence that woody chippings necessarily produce temporary nitrogen depletion particularly if used as a mulch.  I can't be sure where this misconception has come from but it sure is tenacious. 

One of the findings about misconceptions is how difficult it is  to change them. The attitude; "it doesn't matter whether you are right or wrong, what matters is whether you are sure." can be adopted by the religious and conspiracists but should not be the mantra of  the scientist. 

What irritates me a little is the way people use science to debunk science.  You can't logically do that.  You need to question the evidence.  Dowding does the, " Aha got you."

This is because they do not understand the nature of scientific method.  If older data suggests that there is a lull in global warming then a more recent set of data suggests that this is incorrect, it does not invalidate science.  This is just normal science - as technology improves the resolution of the data also gets better.  Questioning  other people's data is a fundamental process in science.  Scientists are doing it all the time.  They will be very dismissive of other scientists research and challenge them at every turn.  I know because I have been at the receiving end of quite severe dismissive criticism.  However, I would not have it any other way.  I would rather have the criticism than publish research that was not correct. 

This does not mean that science is incorrect just that people are being as rigorous as they can be.  Science research can be a rough and tumble world especially if you are working in a controversial area. However, scientists have powerful methods and big machines that test out theories so if anyone is likely to discover inconsistencies - believe me they will.    A lot of scientists would like to debunk orthodox theories but they need to come up with very secure data to do so.  You have to be right not just sure. 

So the word "proof" and the word "truth"  should not really be applied to science.  I would rather use the word "probably" and, "the weight of evidence suggests at the moment. "  But then I am more of a social scientist than a proper one. 


  1. Very stimulating Anthony
    I think hot beds may still have a roll for amateurs. I remember seeing the hot bed principle used for growing tomatoes in an otherwise unheated glasshouse in France several years ago.
    Pst I think you mean Robert Pavlis earlier in your post

  2. I think you are right about hot beds Roger.
    Oh, I think you are right about Robert. I'll change it just in case.