Article by Vinny Chirayil.
Images sourced from internet. Copyright belongs to their respective owners.
June, 2016
(last edited in 2018)
I recommend saving this lengthy page for offline reading (File, Save Page As)
(last edited in 2018)
I recommend saving this lengthy page for offline reading (File, Save Page As)
***
Quick Drainage & Root Aeration
All bonsai experts will tell you that
bonsai trees need special bonsai soil mix that has good drainage and
aeration, for healthy root development. But these 2 things are not the
sole responsibility of the bonsai soil - the pot also has an equally important role
to play in this but seems to be ignored by many bonsai experts and their
followers.
As you can see, the colander offers far superior drainage and aeration. I have deliberately chosen a large colander and tiny bonsai pot to give the bonsai pot an advantage. If both were of the same size, colander's victory is guaranteed. It would not even be a contest. The size extremes also highlight how much more aeration and drainage happens in a large colander than even a tiny bonsai pot ! (of course, this is a display bonsai pot, not training pot and is used just as an example).
I am aware that colanders are used for air pruning the roots but my focus here is only on drainage & aeration. Air pruning pots have 3 benefits - air pruning, better drainage & better aeration but many bonsai artists & experts naively think that they have only 1 benefit, of air pruning. Anyway, back to the topic at hand.
Good drainage and aeration begins
with the pot, not with the soil !
That comes later.
with the pot, not with the soil !
That comes later.
Yet, I do not hear bonsai experts talk about colanders, fabric pots, net pots, air-pots, air pruning pots etc. but talk volumes about bonsai soil, some even importing it all the way from Japan ! Why so much fuss over the soil and ignore the equally important pot ? In many of the expert videos I have seen online, the training pot is either a big bonsai ceramic pot, clay pot, wooden pot, thermocol box or a plastic pot. None of them can match a similar sized colander (or pond basket or air pruning pots for bigger plants) in terms of drainage & aeration.
"Only soil drainage matters !
Pot drainage does not matter."
If you believe this nonsense, then please read the comments of this video. It will be enlightening for you, regardless of your experience. Seriously. And I welcome you to prove me wrong - after reading the comments fully.
Why buy / prepare bonsai substrate having good drainage & aeration and put them in pots / containers which are poor in both areas ? Are many experts and their followers ignorant about basic horticultural science ? I could be wrong but it seems so. The design for small and shallow bonsai pots is fine but it makes no sense at all for deeper pots.
Why do so many people across the world, prefer low density circling roots over high density air-pruned roots, whether it is bonsai or container gardening ?
Innovative custom training pots by Vance Wood and Jay Wilson (far right).
Surprisingly, even the newcomers to bonsai have no doubts on the pot, it is all about soil and other stuff ! The experts "say" the roots need oxygen in their videos but I see them using pots / containers with low air contact. Even the best bonsai soil is not magical, it cannot replicate a colander type pot's functionality. The only advantage a bonsai pot offers is better looks, which is hardly necessary at the training / growing stage.
I have seen some bonsai experts use
colanders to grow bonsai and assumed that they must be aware of the
science behind its benefits, else they would not use them. But I was
surprised to see some of them use plastic cups for seedlings / cuttings, with
very few holes (that too, at bottom only) and having root bound plants
eventually. Yes, manually pruning the root solves it (after the problem has
developed) but why create the problem at all, in the first place ? Is prevention better or cure ?
Besides, manual pruning wastes lot of root mass & growth time bcos of the need to keep roots short. Air-pruning of roots, on the other hand, keeps the roots not only short but also more densely packed and wastage is minimized during repotting.
Poor drainage & aeration. No air-pruning. Root bound plants.
The same ignorance is visible in many air-layering examples online, experts included.
Colander (or even a net pot) helps there too. Why is this so difficult to understand ?
Net Baskets - looks like colander, but isn't.
Use them only after drilling / melting multiple holes on base.
On YouTube, I have seen a bonsai expert and some of his followers using pots like these. I easily misunderstood them to be colanders since it was filled with soil and I could not see the base (till I saw another video of theirs, recently). It is not a colander but a small net basket, probably meant to hold stationary, kitchen or food stuff. It has has poor drainage, only partial aeration and limited air-pruning. Will surely produce circling roots, if used as is. The last row of holes is 1-2 cms above pot floor level and retains water. This pot becomes a fully functional colander ONLY AFTER drilling / melting holes on the base. And that is how I use them.
If you cannot get net pots like
these, then drill / melt more holes on your plastic cup. I sometimes
think people into hydroponics / aeroponics know more about root science
than bonsai people.
I do not accept the "results speak for themselves" logic. That is so lame. There are multiple ways to get results and this whole article is about efficient vs inefficient methods. I am imagining a man with a traditional axe, standing proudly, next to the fallen tree and naively say "results speak for themselves, son" to the new guy with a chainsaw :-)
I do not accept the "results speak for themselves" logic. That is so lame. There are multiple ways to get results and this whole article is about efficient vs inefficient methods. I am imagining a man with a traditional axe, standing proudly, next to the fallen tree and naively say "results speak for themselves, son" to the new guy with a chainsaw :-)
Even for a tiny pot as shown above, I use multiple holes at the bottom. Read the beautiful story above, to understand why. Another similar sized container had only 4 holes at the bottom center, as a test for a same age seedling and the roots haven't come out yet. I will surely find circling roots inside, when I re-pot them later.
The number
of holes in a pot (both side & bottom) is a good indicator of a person's awareness /
ignorance of the concept of good aeration and drainage.
This is not just restricted to bonsai alone but extends to all plants in containers and the people and businesses related to them, including horticultural / agricultural universities, plant nurseries, bonsai nurseries, pot manufacturers, garden shops, bonsai clubs, bonsai training courses etc.
These shallow bonsai pot designs for the finished bonsai trees are fine. The problem is in the deeper pots used in the training / growing stage of bonsai trees. I hope that is clear.
Pot Makers / Manufacturers
Ok fine, the ready-made traditional training / grow pots are poorly designed for drainage and aeration. But why the hell do people who make their own pots continue the poor ancient designs ? Why don't they or even pot manufacturers, evolve, instead of blindly aping the Japanese & Chinese traditional designs ?
Large bonsai pots made by hobbyists.
Bonsai training pots being sold online. Are manufacturers & buyers both ignorant ?
Such pots should become a rarity, in my opinion.
2 different types of deep training pots.
What is so sacred about having 2 giant holes in a bonsai training pot ? I just don't get it ! And having to cover it up with a mesh seems so silly & inadequate ! Why not increase the number of holes and reduce its size so a mesh is not even required ? Or let the entire pot floor be a mesh only. The latter is a far superior design & offers uniform drainage ! Why are so few people aware of this ? If you disagree then I am very curious to hear your logic for it. Go on, please educate me.
Watch this to know better - http://instantbonsaiforeveryone.blogspot.in/2015/10/air-pruning-roots-automatically.html
I also recommend feasting on the content at air-pot.com (all 3 categories) and implement the same with a simple colander.
Watch this beautiful pottery making video - http://youtu.be/UHRA8NJKCKY.
Talented artist but seems to be ignorant of the basic concepts covered
in this article. You can find many people like this online, including
brand name pottery experts ! Please note that I am not picking on any
particular individual but merely showing how surprisingly popular this 2
hole mindset seems to be.
Why are so many people resistant to
having multiple drainage holes ?
Either they go for minimal holes (1-2) or completely skip it, like in the case of fake colanders mentioned earlier. Yet, they go thru lot of trouble to use bonsai soil with good drainage and aeration. I strongly suspect that such people are blindly practicing and preaching things, without a clear understanding of the science behind it. Feel free to correct me. I am curious to know how you are going to defend this :-)
***
I initially thought the ceramic pots won't have strength if its floor is full of holes but clearly that is not the case at all :
Check out more ceramic colanders on my Pinterest board.
If only these pottery artists made bonsai pots also.
If only these pottery artists made bonsai pots also.
I would expect people who make their
own bonsai training pots, to incorporate multiple holes like these,
instead of just 2 giant holes, unless they are ignorant about basic
horticultural science and blindly ape some ancient traditions, which,
for the non-Japanese, aren't even theirs to begin with !
Bonsai is a mix of art and science. I
am not questioning the expert's artistic knowledge but their scientific
knowledge. I agree I am a newbie to bonsai and I cannot compete with
expert-created bonsai. And I have total respect for their bonsai art.
Its the science part of it that I have a major issue with. What stops
them from using pots that have good drainage and aeration ? Do I need
decades of experience and a house full of awards to ask this simple question ?
If I were to teach bonsai, I would talk about pots first. My students have to know what a huge difference the colander type of pots make for good root development & faster growth. Bonsai soil mix comes only after that. They need to know that roots need oxygen, they need to at least have a theoretical awareness of aeroponics (roots suspended in air, breathing oxygen, with periodic spraying /misting of water) and that over-watering, wet roots or wet soil is not the real problem - lack of oxygen for roots is.
It is common for tree roots to
break into underground water pipes and drain pipes and thrive there, in a
natural aeroponic environment. Now, I am not advocating aeroponics for
bonsai but it illustrates the role of oxygen for healthy roots and
faster plant growth.
Why is this important ? So that you DO NOT use poorly designed training pots with minimal air contact, for your bonsai, just bcos some ignorant experts or nurseries use them or manufacturers sell them !
Why is this important ? So that you DO NOT use poorly designed training pots with minimal air contact, for your bonsai, just bcos some ignorant experts or nurseries use them or manufacturers sell them !
Bonsai Education
Judging by the curriculum of the
beginner and intermediate bonsai training courses offered by the reputed
Bonsai Empire, I strongly suspect that their students will be ignorant
of all the basic stuff I have covered here (please correct me if I am
wrong). Their courses might be good but they seem to have skipped a
basic but key knowledge even in the beginner's course - http://www.bonsaiempire.com/courses/beginners-course
Here is another course - http://www.bonsailearningcenter.com/classes.html
The pots seen on their page scream ignorance of the very concepts I
have described till now ! Do you still feel that the horticultural
knowledge of many bonsai experts and their followers is good ?
Let me repeat this again - the number of holes in a pot (both side & bottom) is a good indicator of a person's awareness / ignorance of the concept of good aeration and drainage. Their traditional pots speak louder than their modern words.
Colander Will Dry Up Faster
Yes, but rejecting perforated pots for this reason is like rejecting jet engines bcos they drink lot of fuel and instead, opting for more fuel efficient but ancient propeller engines. Bonsai = shallow containers = more watering. It would be ironical for bonsai artists to complain about this.
Imagine the same substrate put in a same sized colander and bonsai / plastic pot. Sure, the colander will dry up faster. But so will your fast-draining bonsai substrate when compared to soil / sand & your shallow display bonsai pot when compared to a medium sized nursery pot. That is not a problem once you know the solutions available for that.
Imagine the same substrate put in a same sized colander and bonsai / plastic pot. Sure, the colander will dry up faster. But so will your fast-draining bonsai substrate when compared to soil / sand & your shallow display bonsai pot when compared to a medium sized nursery pot. That is not a problem once you know the solutions available for that.
You can cover the top of the colander soil with rocks, pebbles, moss, wet cloth, mulch etc. to minimize water evaporation.
If you have a busy life and can water the plants just once a day only then the bonsai soil in the colander needs to have more water retention than what you would use in the bonsai pot. This can done by adding more cocopeat, peat moss, sand or even ordinary soil.
If you have a busy life and can water the plants just once a day only then the bonsai soil in the colander needs to have more water retention than what you would use in the bonsai pot. This can done by adding more cocopeat, peat moss, sand or even ordinary soil.
Extra oxygen supply boosts performance everywhere.
Stop fighting it and embrace the truth.
E V O L V E - 3d printed, air-pruning, display bonsai pot by Peter Bone !!!
I am sure even ceramic pots can come close to this and would have the desired weight too. There is another option of this same shape, with holes only on bottom and the sides are plain, designed by Peter and available here - shapeways.com/product/. Even plastic garden sieves can be a nice alternative, with many shapes and sizes available - garden sieves on Amazon
Notice that the holes are wider inside the 3d printed pot than the outside, just like the black air-pots. This helps in guiding the new roots into the hole and they get pruned before getting a chance to escape. If you simply drill or melt holes into a plastic container, usually the number isn't high enough and hence roots do skip a few holes before getting pruned eventually. You might even get circling roots, sometimes. The shapeways.com site even allows you to upload and 3d print your own pot designs, with a choice of material too ! If you want to clone an existing pot or object, they can even 3d scan and print it for you.
Questions I am Still Wondering About
- Why do so many bonsai artists use bonsai pots for training their trees ?
- Why sacrifice functionality for looks, so early in the life of their bonsai ?
- Are they so desperate to convince themselves & others that they have a bonsai, with a bonsai pot ?
- Or are they ignorant about basic horticultural science ?
- Will they only follow what the Japanese bonsai masters do or approve of ?
- Will they only follow what the Japanese bonsai masters do or approve of ?
- Why not improvise pot designs instead of merely copying ancient & poor designs ?
- Does any other art form have such a slavish mindset ?
Yes Morpheus, I totally agree !
Note : I might be stepping on
people's toes, but it is with a good intention of curing people's
ignorance of basic horticultural science. I am not paid by any brand to promote
anything here. Just take the concept only, like me.
***
Thanks for featuring my pot (3d printed one). I should say that the version I printed is not waterproof as I found out when it disintegrated. However, printed in another material such as porcelain and it should be fine.
ReplyDeleteHi Peter, its great to see your comment here. Your pot design is an awesome design & totally unique in the bonsai world ! I love it ! You should consider licensing it to some pot maker. Has your pot design been reviewed anywhere online ? Links are welcome :-)
DeleteHi Vinny, thanks for this highly interesting blog!
ReplyDeleteI started to melt slots in all my plastic grow pots and can´t wait for next summer to see the difference.
Doung this i took a close look at the forms of the roots I noticed that a small thing can make a huge difference: if a hole in the bottom of a pot is just a few millimeters away from the side wall the roots often don´t find it and grow in circles. If the hole touches the side wall, goes around the edge or is placed at the lowest part of the side wall, it reliably achieves air pruning.
In one of your videos you show a picture of how you would design a ceramic pot, but you did not place the holes right next to the walls – changing this might be an improvement, I believe.
Unfortunately it´s hard to drill additional holes in existing ceramic pots.
Did you hear of the "Walu"-system developed by the Austrian Walter Poetscher? He achieves good air pruning without holes in the sides by shaping little edges in the pots that redirect the roots to slots in the bottom: http://www.bonsaischalen.at/walu-system-neu/ - the website is in German only. If you give me your mail address I´ll tell you more in private.
You often ask why people stick to the old system. Of the +- 30 bonsai enthusiasts in the Vienna Bonsai Club only one uses baskets for air pruning. I think people are generally skeptical about new things (that look different) especially if they´re all in all satisfied with what they´re used too. Lots of brilliant inventions never made it simply because of that. On top of this, bonsai is a hobby where folks love to imitate traditions (which is already hard enough) so maybe they are very busy with this. And a traditional pot is much nicer to look at than some plastic kitchen tool, of course. Even in a private garden they like too look at the trees wearing "suits and ties", not "t-shirts and shorts", to use your words.
Not everybody is a pioneer like you, so even for grow pots it might take time till this technique spreads.
My most important question to you: do you know many people who use air pruning for growing bonsai? Do you think the idea is spreading quickly or slowly?
Please be so kind and send me a private address to lindworsky(at)yahoo.de, then I´ll be glad to tell you why I ask all this.
So long,
Jens
Thanks Jens for your feedback. Had mailed you my response sometime ago.
ReplyDeleteWhat if the colander I use has a hole same size of my medium (pumice) eventually the medium inside the colander will wash out. Any suggestion?
ReplyDeleteWith interest I learned from you new in a bonsai. I am not especially keen on it, but with your help, perhaps, I will be engaged in it. Thanks for interesting and useful information! Imitating old traditions, people don't look for the new. I am very glad to acquaintance to you!
ReplyDeleteYours faithfully. Tatyana Popova.
OK...wow! That was a doozy. Here's how I feel about pot drainage and aeration: it's an integral part of tree development. It's not an integral part of sustaining a beautiful bonsai. Allow me to explain (as I explain my reasoning, understand that is the way I see it NOW but that this viewpoint is dynamic and changes as I learn more).
ReplyDeleteTake a look at this paper. It was helpful for me as I did my own homework trying to answer the question, "how exactly does air pruning lead to a healthier, larger potted tree?":
Michael D. Marshall, Edward F. Gilman; Effects of Nursery Container Type on Root Growth and Landscape Establishment of Acer rubrum L.. Journal of Environmental Horticulture 1 March 1998; 16 (1): 55–59. doi: https://doi.org/10.24266/0738-2898-16.1.55
What I found to be most interesting was the table of data at the bottom (if you cannot gain access to the article via university/local library database collection and are interested in reading it, shoot me an email).
In this table, data averages are shown for seven different types of nursery container. There are three columns: 1. Deflected root length, 2. Deflected root mass, and 3. Total root mass inside "root ball" (root ball being quoted by me because at this moment I am unsure what the authors' *operational definition* of "root ball" is, i.e. is this to say total mass of the *entire* collective sum of roots within container?). While I recognize this is merely one experiment...with limited sample size...relating to just one cultivar of Acer rubrum...a species which generally has a shallow root system... I found this table of data to be extremely informative overall.
As it relates to this blog post, I will say this: there is no suggestion that air pruning container types will lead to superior trees. In fact, if the air pruning container is tall and skinny, the tree's root mass will be markedly lower than every single one of the other containers. Conversely, a "low profile," short and stocky air pruning container came in near the top in terms of total root mass.
Deflected root mass is important too though, because with bonsai we want to create a quality nebari, which means we do not like roots with >45 degree angles protruding from center of root ball. The table of data shows quite clearly that a tall, skinny air pruning pot leads to very high levels of vertical deflection of roots, meaning these roots are useless to the final design. The low profile air pruning pot had solid numbers wherein root deflection was not such a problem.
Overall I will just say this: air pruning pots certainly have their benefit, but it would be a mistake to think that these pots as a whole - all shapes and sizes - offer a smoother transition, or are even horticulturally appropriate for, bonsai.
More bluntly: if using air pruning pots, make sure the pot is low profile -- shorter and wider -- as opposed to taller and skinnier. Otherwise, you may as well have just stuck to the classic black nursery container!
On the topic of your curiosity as to why bonsai pots are classically two large holes, I would say this: root regeneration takes energy. The goal of sustaining a small tree in a container is to focus the very limited energy supply on creating foliage, and allowing the foliage to harder in order to hit net-zero energy loss (it is only once foliage hardens, that a tree begins to primarily store the photosynthates produces by that foliage, as opposed to pumping water and nutrients up at high levels to support the excessive transpiration and ongoing growth of an unhardened leaf). In other words, we want the root system to be focusing its energy on the foliage, not itself! Air pruning inherently causes root die-off, which while negligible on a case-by-case basis, does add up to some degree of energy expenditure.
ReplyDeleteTo remove all scientific rationale from this long-winded comment, consider the old adage: "if it ain't broke, don't fix it." I have seen breathtaking bonsai which are contained in the classical pots. Could they have been MORE breathtaking if they were in a pot with an entirely mesh bottom? Maybe! But those trees are extremely healthy, even without the [in your eyes] absolutely necessary mesh bottom.
Another thought I just had is that, while people may understand and appreciate the value or greater aeration and drainage offered by container type, these people still have a schedule, and lives and jobs and responsibilities outside of bonsai. Me? I am a plumber, and I simply cannot water my trees four times a day in the heat of summer, because i'm out there working. The cost of greater aeration and drainage is that the tree requires more frequent watering. Overall, I would much rather have a plant in a standard container that retains enough water to keep the tree alive and healthy, albeit growing at a slower rate, than to come home from work and find all of the leaves on my Wisteria sinensis have withered because it was terribly hot that day and the roots dried up.
You shouldn't be so willing to look down on others who plant their trees in standard pot types, unless you are *absolutely positive* they are "ignorant" and not just "diligently informed and responding accordingly to the responsibility inherent to living an adult life." Blindly labeling others as ignorant when they could very well be informed and making a choice based on a variety of factors, well, it just makes you seem…ignorant.
This comment has been removed by the author.
ReplyDeleteEdited because I forgot to close the parenthesis, lol:
DeleteOne more thing. It is completely insane to me that you proclaim [countless times in this extensive diatribe] the ignorance of people who don't rely on pots with high aeration and drainage, yet, you include no scholarly articles, no research, no citations of any kind. In other words, you have a very strong opinion about the lack of scientific awareness in others, all the while, you ironically neglect to include any scientific basis for your opinions.
Charles Munger lives by the mantra that if he cannot tell his opponent's argument better than they can tell it themselves, he refrains from entering his opinions on a matter. This is a mindset I wish more people, like you, would take on. Clearly, you have not done nearly as much homework as someone with such strong convictions ought to have done in order to support those convictions.
The word "ignorant" appears eight times in this blog post, and the guy who made the post doesn't even prove beyond reasonable doubt that he's done his homework! (making a video of water draining out of a pot isn't homework, it's anecdote.) For someone who took so much time creating a post about the lack of scientific awareness of many bonsai hobbyists, it's shocking how low the amount of scientific evidence you've provided is.
As a beginner in bonsai myself, I can answer your question about training young plants in traditional pots: it's not to "convince" myself that I have a bonsai -- I surely know I do not -- but just so it looks nicer. I realize that I'm trading time (and perhaps even quality) for the current aesthetic, but I like looking at the traditional ceramic pots more than training pots/colanders/whatever. Since bonsai is an art, the aesthetic, even in the beginning and even in the process, can't be ignored. At least not for me.
ReplyDelete