Author Topic: How would you like your roots cooked?  (Read 2865 times)

nathanbs

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How would you like your roots cooked?
« on: December 06, 2012, 03:26 AM »
This is a follow up to an "interesting" discussion that was had here at BSG regarding "cooked" roots on several of my JBP that ultimately let to their death. The discussion for those of you that were fortunate enough not to have to have read it was whether or not roots can get cooked if you have too large of a soil particle which would in essence give you very large airspace where larger amounts of vapor could/would exist and given a high enough temp the roots could cook from this hot vapor. I iterated and re-iterated that my trees never were allowed to dry out. Following my comment there was some laughter of which i took offense to and I then stated that Ryan Neil shared this idea with me. Out of curiosity or because they thought I was a liar they emailed Ryan and asked whether or not this was the case. Ryan replied that soil particle size cannot cook the roots.
As promised I had the opportunity yesterday to go back over this info with Ryan and here is what he said. The number one reason why soil particle size could have caused my trees to have been adversely affected during very hot weather is that the large particles do not promote fine, healthy, strong, dense root growth that would help the tree better tolerate the heat and be able to utilize the vapor. He also stated that roots could die from excess water during the hottest part of the day starting to cause root rot(he clarified that this would have to have been a ongoing condition). He agreed that finer soil could insulate the roots better during hot conditions.
So although fairly different from my original understanding the cause(heat + large particle size) and effect(dead roots=dead tree) are the same. For the record on an earlier phone conversation he agreed you could cook an egg on a bonsai pot and roots could get fried during that type of heat with or without water.
The demise of the trees appeared to have happened over the course of about 2 weeks and there wasn't yellowing like with excessive water during normal temps but more of a grey muted lifeless color like when sap flow stops. Hope this helps set the record straight and hopefully a few can learn from my mistakes
 

Anthony

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Re: How would you like your roots cooked?
« Reply #1 on: December 06, 2012, 04:01 AM »
Interesting Nathanbs,

My trees are grown in full sun, and my friend has his over asphalt on the western side of his house, also full sun. Many are mame' and I have yet to experience any over heating or see it by my friend.
We both use compost in the mix, so it is not totally inorganic, and one of the iinorganics is a porous material.

However our humidity does not dip below 45 % at the highest temperature of the day during our dry season.
We also do not cross 93 deg.F daytime or so,nor dip below 70 deg.f at night.

Now with regard to soil particle size - I use around 5mm, do you know how much smaller one has to go to get the finer roots effect ?
Thanks in advance.
Anthony
 

nathanbs

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Re: How would you like your roots cooked?
« Reply #2 on: December 06, 2012, 09:58 AM »
The trees that I had a problem with were on soil that was 1/4 - 1/2 and we occassionally peaked over 100F. I no longer use anything over 1/4" and the same species of trees that were in similar size pots and in the same location that had smaller particle soil did just fine
 

0soyoung

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Re: How would you like your roots cooked?
« Reply #3 on: December 06, 2012, 12:02 PM »
So what were the temperatures in your soil?
 

bigDave

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Re: How would you like your roots cooked?
« Reply #4 on: December 06, 2012, 12:16 PM »
  I no longer use anything over 1/4" 

Very good Nathan, problem solved , thanks for sharing your hard times

 
 

nathanbs

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Re: How would you like your roots cooked?
« Reply #5 on: December 06, 2012, 01:11 PM »
So what were the temperatures in your soil?

never probed, don't have a probe. Sorry
 

Markyscott

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Re: How would you like your roots cooked?
« Reply #6 on: December 06, 2012, 09:33 PM »
Thanks for sharing your conversation with Ryan.

Here in south Texas, I have many trees growing in a medium similar to that which you describe.  This includes quite a few tropicals, junipers, pines, and maples.  In fact, I Have a couple of Hollywood junipers growing in coarser medium than you describe (3/8"-1/2").  I also have quite a few orchids growing in a medium with an even coarser partical size - up to 1" in diameter.  All have seen temperatures far in excess of 100 degrees, sometimes for quite long stretches.  Perhaps its dumb luck (I've been blessed with that in the past) or perhaps there something particular about the climate in Houston (like the 200% humidity) which allows for success with such a medium.  But it's possible to grow trees in a warm climate using a medium sieved to 1/4-3/8" partical size.

One difference in care that I shared with you before is that I water more frequently than once per day in mid-summer and I never let the soil dry out to a depth of 1" below the soil surface as you described.  I subscribe to the Walter Pall school of thought on watering when using a modern substrate:

http://m.youtube.com/watch?v=ccOGUj9b6dc&desktop_uri=%2Fwatch%3Fv%3DccOGUj9b6dc

in short "water often and then water some more" - I believe that his watering discussion comes at about the 3:20 mark in the second video in the series.  But it sounds as though you've ruled out this possibility.  I'm glad you've found a solution that works for you.

Scott
 

nathanbs

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Re: How would you like your roots cooked?
« Reply #7 on: December 06, 2012, 09:55 PM »
You're welcome. To be specific this only happened on 3.5 JBP(I rescued what would have been the fourth one by removing the top 2.5-3" of coarse soil and replacing it with 1/4" or less size. It was a akadama, red lava, hyuga, mix equal parts with 10% granite and a very small amount of charcoal. Maybe if the mix was a little dryer I could imagine watering more than once. For credibility of a JBP mother daughter tree in a 1.5 inch deep pot with 1/16-1/8" of the same mix. I had to water it 2x a day during the really hot days. This tree did really good while the others died??
 

bwaynef

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Re: How would you like your roots cooked?
« Reply #8 on: December 06, 2012, 09:59 PM »
For credibility of a JBP mother daughter tree in a 1.5 inch deep pot with 1/16-1/8" of the same mix. I had to water it 2x a day during the really hot days. This tree did really good while the others died??

Are you saying that you only watered the other (3.5) trees 1x a day while this one (in a smaller version of the same mix) was watered 2x?
 

nathanbs

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Re: How would you like your roots cooked?
« Reply #9 on: December 06, 2012, 10:29 PM »
Yes but keep in mind the pot is only about 1" deep. Watering the rest of JBP in smaller soil but deeper pots 1 X a day during the summer proved to be too much as they had definite signs of over watering at the end of the summer.
« Last Edit: December 06, 2012, 10:33 PM by nathanbs »
 

0soyoung

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Re: How would you like your roots cooked?
« Reply #10 on: December 06, 2012, 10:49 PM »
Let me suggest that your tree's roots really don't like temperaures above 95F and that they start dying at temperatures above 105F. Let me also suggest that you keep your trees in the shade when it is hot. Further, let me suggest that one can use a wet white towel over the pot to keep the temperature down. White to be reflective of the sunlight. Wet to affect evaporative cooling to keep your roots from cooking. It really isn't about watering and soil, even though watering in the heat of the day will cool the roots (but drowning them isn't such a good thing).

Oh, and DO spend $5 on a thermometer probe next trip to the grocery store or buy a $25 if you want a nice digital one with a thremistor probe. A little data will be very enlightening. Consulting the Warnell School of Forestry and/or reading some papers on 'supraoptimal tempertures' will enlighten you further.
 

Markyscott

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Re: How would you like your roots cooked?
« Reply #11 on: December 06, 2012, 11:45 PM »
A couple of additional suggestions:

1) Dave Degroot has a wonderful series of articles in International Bonsai.  In one of these articles "DeGroot, D., 1993, Bonsai Technical Notes #2: Light Sensitive Growing Areas, International Bonsai, 1993, 32-37" the design and construction of a simple, low-cost misting system is discussed, as well as the design of shade cloth structures that can reduce radiant heating.  For the misting system, Dave suggests 2-3 cycles of 1-3 minutes each during the hottest part of the day will generally be sufficient to protect your plants from overheating. 

2) Boon has us layer sphagnum moss on top of the soil after repotting to reduce loss of moisture through evaporation. 

3) In my yard, I have an overhead sprinkler that comes on during the afternoons in July and August and pretty much soaks everything - trees, water, benches, soil - I think this helps as well due to the effect of evaporative cooling.  I've noted that the temperature on the benches will be reduced by several degrees after the sprinkler does its job.

4) My bald cypress trees pretty much sit in a shallow tray of water during July and August - I just top them off in the afternoon. 

But reducing the grain size of your substrate can help as well because a finer-grained medium is more water retentive.  Lots of ways to skin a cat - it's just a matter of finding what works for you under your growing conditions ... which it sounds like you've done.

Cheers
Scott
 

nathanbs

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Re: How would you like your roots cooked?
« Reply #12 on: December 07, 2012, 01:12 AM »
Thanks for the advice guys :) I'm going to get a temperature probe for sure. But I think my only real problem was the soil particle size as my other 196.5 trees did fine. I'm reading degroots book as we speak. I think he covers all of his articles in the book if not I'll track those down. I do a soil top dressing now as well but only on my repots. Some day I would like to set up an overhead watering system for the summer days and lazy days ;)
 

Markyscott

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Re: How would you like your roots cooked?
« Reply #13 on: December 07, 2012, 01:13 AM »
Also - soil in a shallower pot will have a higher overall water saturation than an equivalent volume of soil in a deeper pot.  For example, Spomer, A.L., 1980, Container soil water relations: Production, maintenance, and transplanting, Journal of Aboriculture 6, 315-320.

 

nathanbs

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Re: How would you like your roots cooked?
« Reply #14 on: December 07, 2012, 01:22 AM »
Without having read the source you listed I presume from gravity?