H.Harrington VS AI

[isid]

In his Bonsai4me July 2025 Newsletter; H harrington writes :
" With Summer nights now into double figures, and this can reduce the ability of trees to release co2, something they do at night as part of a process known as as respiration. (I’m very much simplifying things here but want to discuss the problems associated with warm night temperatures rather than the photosynthesis gas exchanges).
The warmer our trees are at night, the less co2 that can be released and this impedes growth. It’s been long known that nurseries in rural areas or at elevation, where there is a larger difference in day and night temperature, achieve better growth rates than in areas where day and night time temperatures are relatively as warm as each other, and this is the reason."

This statement seems odd to me so I asked AI, and here is the answer:

The statement contains several inaccuracies and oversimplifications regarding how night temperatures affect tree respiration and growth.

• Trees (and plants in general) do release CO₂ at night through the process of respiration, but the relationship between night temperature and respiration is not as straightforward as the statement suggests.
• Warmer night temperatures generally increase the rate of respiration, causing plants to release more CO₂ at night, not less357. This increased respiration can, in some cases, reduce overall plant growth because more of the plant's stored energy is consumed for maintenance rather than growth7.
• Recent studies show that nocturnal plant respiration declines through the night even at constant temperature, but temperature still plays a significant role142. The process is influenced by both temperature and the availability of respiratory substrates, and not solely by temperature14.
• The idea that nurseries at higher elevations or with greater day-night temperature differences achieve better growth is partially supported, but not for the reason given in the statement. Growth benefits are likely due to a combination of factors, including reduced night-time respiration losses at cooler temperatures, rather than a reduced ability to "release CO₂"35.
• The claim that "the warmer our trees are at night, the less CO₂ can be released and this impedes growth" is incorrect. In reality, warmer nights typically lead to more CO₂ being released through respiration, which can reduce growth efficiency because more carbon is lost7.

 

[Wires_Guy_wires]

He's not a biologist, simply put.
Take his biology lessons with a bucket of salt. I've been blown away a couple times already by false third-hard statements obviously not investigated.

 

[Bonsai Nut]

Perhaps he is conflating respiration and transpiration? And also - that AI response has issues as well.

 

[PA_Penjing]

Im with @Wires_Guy_wires , There's some incredible artists in our circle but you can't be elite at every aspect of our hobby, it's too far reaching. I've heard Ryan Neil say terribly inaccurate things about non native trees and taxonomy. He's an incredible artist and visionary, but that's not his strong suit. Frankly it doesn't matter, because he's successful. Personally I don't take dendrology lessons from artists, there's scientists and research papers for that. It's not even that these guys are dumb or anything like that, everyone trips over words. And when you start translating article from Japanese to English you're bound to add to it.
This hobby is like golf, there's infinite things you can tweak or improve on but you'll never be 100% there. That's actually probably every sport or hobby honestly, but golf is especially hard imo. My morning espresso hit, I'll stop here

 

[99 Mile Creek]

I cannot say which is the right answer. But...

I have seen many mistakes and incorrect answers provided from AI, oftentimes their sources pulled directly from a comment such as a forum/comment-based websites...once and answer provided matched up with a random comment from Reddit. Didn't make it wrong, just made me more wary.

I would not put all of your stock into everything AI says (not into anything you read, really). Unfortunately, we see AI-generated answers at the top of a Google search, nowadays, and my children are constantly repeating their quick google searches to me when looking something up. I have caught a ton of mistakes just from that and have been instructing my children to bypass the AI answers altogether, going back to teaching good research habits, weighing multiple answers against reputable sources while also utilizing critical thinking...and applying, if applicable, our own findings/experiences.

For instance, there is a lot of subjective advice provided in bonsai. Ask AI what substrate mix is best for bonsai, it will probably give you an akadama, pumice, lava answer along with specie dependent mix ratios...doesn't mean that it's necessarily right. It means that it has been tried and found to be effective by a large sample size on the internet and/or found in documented, traditional practices. I do not use that mix as I need my substrate to hold more water, the traditional Japanese mix works well--especially in Japan where they have a wet climate and they need fast-drying substrate (at least that's my understanding).

And research sources cited from AI response may be right, but: Who did the research? Did they cut corners in order to publish a paper? Was there confirmation bias? Are there any publication biases to consider? What was the motivation to publish? Were there any confounding variables? Peer-reviewed research does not automatically mean objective.

And where I would rather say, "Get your information from a book written by a PhD(s) in botany..." even then, I read with skepticism.

AI is a great tool (and continuously improving), research is very important data to consider, most textbooks are mostly the greatest sources, but I would never put blind faith into any one thing, AI-generated least of all.

 

[Glaucus]

Maybe his statement has to do with stomata being more closed off because of higher temperatures? And this allowing for less gas exchange. I am not aware what exactly the bottleneck of growth would be during warmer summer nights. Of course once a plant gets too warm in summer, many chemical reactions stop functioning optimally. And too much light or too little water can also be stress factors.
But the buildup of CO2 that clogs up the plant is a strange concept. As if warm air can't hold all the CO2 comparable to warmer water containing less dissolved oxygen.

You can plug this into AI to find which cellular or biochemical process the AI associates with a confusing phrase or statement you find. And then use a reliable source to read up on the details of this process. So not the AI itself. And this reliable source can be wikipedia, a random youtube video, or even a college level textbook. That would be the proper way to use AI here. AI can be quite good at picking up at connections of confusions made by other people that you may not pick up on. You could also ask the LLM models to find you sources or studies. And then check if those studies actually exist and read those.

The AI is correct here that the warmer it is, the more rapidly chemical reactions happen. And the more sugars are burned during nighttime. And the more CO2 would be released. The question is if such an increased rate of metabolism is actually useful to the 'personal goals' of the plant. Or to bonsai aesthetics of the bonsai owner of the plant.

It is cool that major bonsai artists start to put their insights into scientific concepts, but often they present their own pet hypothesis as simple facts. And sometimes those have major flaws. Ryan Neil was quite guilty of this at the recent The Trophy. Even going as far as saying that electron microscope imaging of akadama supporter his intricate theories on why akadama is truly special and should be used exclusively for all conifer bonsai. Ryan Neil was doing a big info dump meant to one-up and show off all the other artists there, to establish him as the alpha dog. Which was quite amusing and funny and done respectfully enough. But some of the 'science' was quite amusing. But that I guess is just the way to do science and bonsai together. Have experienced bonsai professionals read up on the science, and come up with their own theories, then share them with others, and see if they hold up.

 

[Wires_Guy_wires]

I cannot say which is the right answer. But...

I have seen many mistakes and incorrect answers provided from AI, oftentimes their sources pulled directly from a comment such as a forum/comment-based websites...once and answer provided matched up with a random comment from Reddit. Didn't make it wrong, just made me more wary.

I would not put all of your stock into everything AI says (not into anything you read, really). Unfortunately, we see AI-generated answers at the top of a Google search, nowadays, and my children are constantly repeating their quick google searches to me when looking something up. I have caught a ton of mistakes just from that and have been instructing my children to bypass the AI answers altogether, going back to teaching good research habits, weighing multiple answers against reputable sources while also utilizing critical thinking...and applying, if applicable, our own findings/experiences.

For instance, there is a lot of subjective advice provided in bonsai. Ask AI what substrate mix is best for bonsai, it will probably give you an akadama, pumice, lava answer along with specie dependent mix ratios...doesn't mean that it's necessarily right. It means that it has been tried and found to be effective by a large sample size on the internet and/or found in documented, traditional practices. I do not use that mix as I need my substrate to hold more water, the traditional Japanese mix works well--especially in Japan where they have a wet climate and they need fast-drying substrate (at least that's my understanding).

And research sources cited from AI response may be right, but: Who did the research? Did they cut corners in order to publish a paper? Was there confirmation bias? Are there any publication biases to consider? What was the motivation to publish? Were there any confounding variables? Peer-reviewed research does not automatically mean objective.

And where I would rather say, "Get your information from a book written by a PhD(s) in botany..." even then, I read with skepticism.

AI is a great tool (and continuously improving), research is very important data to consider, most textbooks are mostly the greatest sources, but I would never put blind faith into any one thing, AI-generated least of all.

Grapevining or parroting by long term hobbyists is no different in my opinion. They too are trained by learning language and knowledge presented to them by others.

Stomata opening and closing however, is something I'd trust AI with knowing. It's been widely studied.

 

[MGTT]

Fwiw, there’s a chapter in Bonsai Heresy discussing day/night (DIF) temperature differential. There are more details in the book, but my takeaway was a larger DIF is associated with greater growth in temperate trees and conifers. There are references to studies included, and the mechanism for this is identified (giberellins). Note-There was no discussion on CO2.

 

[BobbyLane]

Cant comment on the scientific side of things. Whats clear to me is mini heatwaves can be a blessing and a curse. Weakly rooted trees may struggle, while stronger, well established root systems will thrive. Already seeing multiple flushes on my Beeches and strong growth on Elm.

I remember the last heatwave we had in the UK, for a two month period during the pandemic. I remember my big Zelkova producing 4 strong spurts of growth.

During these periods its a great chance to push trees harder than usual. Strong rooted trees should respond.

 

[MGTT]

Cant comment on the scientific side of things. Whats clear to me is mini heatwaves can be a blessing and a curse. Weakly rooted trees may struggle, while stronger, well established root systems will thrive. Already seeing multiple flushes on my Beeches and strong growth on Elm.

Do you think it’s a combo of heat and humidity? I’ve noticed similar growth this year, but it’s been wet/humid as well.

 

[BobbyLane]

Do you think it’s a combo of heat and humidity? I’ve noticed similar growth this year, but it’s been wet/humid as well.

Its not been very wet here, our heat is a dry heat. And its been windy. One of my Beeches potted this year, the leaves have suffered a bit, but its still pushing flushes. While a couple others have been fine in direct sun.

 

[nuttiest]

Summer dormancy is an issue when the night temps get above 80F. Less respiration, less water need, likely high humidity in these areas. Some species are exempt unfortuately, grass is one, hemiepiphytes another...