Summer Repotting of Chojubai and Princess Persimmon

[NaoTK]

I took a break from making pots for a couple hours to experiment with summer repotting. Repotting in summer may be advantageous for some species like persimmon and chojubai. We should experiment more with other species.

Princess Persimmon
Professional growers in Japan suggest repotting P.P. in summer. The theory is these are tropical plants and are most active in summer so there is "momentum" to carry the tree through recovery. Apparently the tree will keep its fruit and will have a faster start next year.

This is a true hermaphrodite tree that is overgrown with suckers. The structure is boring so I was willing to experiment with this one.



I pull off the suckers and removed about 30% of the roots, mostly large downward sections I left 3 years ago. I kept the root mass wet while working in the summer heat. I saw lots of active growing root tips which are a lighter color on persimmon.



I put the tree in morning sun and it's been over a week. The leaves have not lost turgidity or anything, like the tree didn't notice the repot. The root suckers are also doing well. My experience with P.P. tells me the critical thing is whether it sets buds before winter frost.



Chojubai
I believe repotting chojubai in summer is now the best practice. Check out the links below from Michael Hagedorn and Jonas Dupuich for more details.
https://crataegus.com/2021/08/06/repotting-chojubai-in-summer/
https://bonsaitonight.com/2018/06/29/repotting-young-chojubai-in-summer/


The large clump on the left was a rat's nest of weeds and suckers and I wanted to reset it.



...After removing most of the leaves and trimming long shoots, then repotting into a wider flatter container.


...After wiring. It seems crazy to repot and wire on the same day but this is what the pros do. I like the multi-trunk mound style so that is what I'm going for here. Michael might make trees with a couple primary trunks.

My greenhouse is way too hot this time of year, so I have it in light shade. The ideal situation is a high humidity warm greenhouse.



cuttings

 

[pandacular]

how are these trees doing now?

 

[NaoTK]

how are these trees doing now?

Amazing! The chojubai completely regrew the foliage in 2 weeks. Didn't skip a beat, it even has flower buds. This is the way. I removed about 30% of roots without barerooting or washing the roots, but I did chopstick and water vigorously after repot.

The persimmon also didn't skip a beat. It has new buds everywhere. The leaves never lost turgidity. But I want to do more summer repots before I'm 100% convinced. The tree I repot had a reasonably well-developed root ball, so I will do one this week on a tree from the field with less developed roots. I also need to see how they perform through winter and next spring before I go and repot all my trees in summer. I also need to kill a tree by removing too many roots in Summer to see how far you can push it (I have shitty trees.)

 

[yenling83]

 

[pandacular]

I won't lie, I almost made a similar pun (How are these trees doing, Nao?) but I didn't want to offend. glad Jeremiah did it for me!

 

[yenling83]

I won't lie, I almost made a similar pun (How are these trees doing, Nao?) but I didn't want to offend. glad Jeremiah did it for me!

haha, it's all out of love and respect!

 

[pandacular]

I've definitely thought about getting a few tropicals just so i can spread out my repot work...glad to see that I don't have to take such extreme measures! Excited to watch this, maybe I'll pick up a persimmon.

 

[hemmy]

I believe repotting chojubai in summer is now the best practice.

What temperature and humidity range is your summer repotting window?

Are they actively extending shoots or is this during a ‘summer dormancy’ between growth extensions?

I’ve considered this in the Midwest but I think it has to be before the Summer Solstice when we are 80s-90F with good humidity and not 90-100F when the winds can be more drying later in the summer.

Thanks

 

[Shogun610]

I should try this next year after how long it took for my persimmon to regain strength last year. I need to find a male Persimmon though in order to fruit mine.

 

[NaoTK]

What temperature and humidity range is your summer repotting window?

I suspect it doesn't matter much and you probably have more favorable conditions than me. Oregon is low humidity and 80-95 in the day and 50s at night. I suspect higher humidity and hotter nights are better.

Are they actively extending shoots or is this during a ‘summer dormancy’ between growth extensions?

In July/August they are actively extending. I don't know if there is a summer dormancy period.

 

[NaoTK]

I should try this next year after how long it took for my persimmon to regain strength last year. I need to find a male Persimmon though in order to fruit mine.

I will completely switch to summer if it pans out

 

[Shogun610]

I will completely switch to summer if it pans out

Yes lmk I shall follow you into the depths

 

[vp999]

I just repotted some of my Chojubai and PP last week also, they seems to responding well despite reducing the Chojubai roots like 50% or more...and its been in the 90s here. Thanks Nao....now send me those PP pics lol.

 

[namnhi]

Amazing! The chojubai completely regrew the foliage in 2 weeks. Didn't skip a beat, it even has flower buds. This is the way. I removed about 30% of roots without barerooting or washing the roots, but I did chopstick and water vigorously after repot.

The persimmon also didn't skip a beat. It has new buds everywhere. The leaves never lost turgidity. But I want to do more summer repots before I'm 100% convinced. The tree I repot had a reasonably well-developed root ball, so I will do one this week on a tree from the field with less developed roots. I also need to see how they perform through winter and next spring before I go and repot all my trees in summer. I also need to kill a tree by removing too many roots in Summer to see how far you can push it (I have shitty trees.)


View attachment 501960

As long as shitty tree you think of is not the one Mary holding for me to wait for the weather to cool down then we're good.

 

[vp999]

As long as shitty tree you think of is not the one Mary holding for me to wait for the weather to cool down then we're good.

Take one for the team man …. How the hell are we ever gonna learn ?

 

[NaoTK]

Let's kick it up a notch. Here is another 30min repot I did during a Teams meeting this morning. We will learn a lot from this!

This is a female in a nursery can, not repotted for 10-15 years



It's a solid sponge of roots. Cannot get a root hook in it.


I had to saw off the bottom half


I removed about 50% of the roots, mostly fat un-ramified sections, keeping as much fines as I can.




I'm not completely retarded, I don't want the tree to die so I removed about 50% of the leaves as well. This was a good opportunity to make big necessary edits. A topic for another thread, I am a firm believer in top pruning with princess persimmon. Even in spring I will top prune aggressively when I do big root prunes and have had great success and lots of back buds.


This will go in morning sun, shade the rest of the day until I see how the leaves hold up. The one I repotted three weeks ago is in full all day sun!


We also get to learn if root cuttings do anything in August. In my experience it can take over a year to get growth from root cuttings so don't give up on them so soon.

 

[jszg]

I wonder what exactly about Chojubai makes it amendable to summer repotting. It could generalize to the rest of the flowering quinces, and possibly other Rosaceae.

 

[NaoTK]

There is a surprising amount of literature on persimmon rooting and nitrogen storage. I think we can build some models about why persimmons suck at repotting and why summer repotting is better.

• Persimmons store most of their nitrogen in the roots in Fall.
• In spring, persimmons draw entirely on this root nitrogen to leaf out. Many other deciduous trees also do this.
  • https://www.sciencedirect.com/science/article/abs/pii/S0304423808002768 I can't access so if anyone has access please send me
    
    

    Frontiers | Nutrient Storage in the Perennial Organs of Deciduous Trees and Remobilization in Spring – A Study in Almond (Prunus dulcis) (Mill.) D. A. Webb

    The annual dynamics of whole mature almond tree nutrient remobilization in spring and the accumulation of nutrients in perennial tissues during the year were...

    www.frontiersin.org
• Therefore, if we cut the roots off in spring we are severely debilitating the persimmons.
• If we repot in summer, the tree is actively generating new growth and not relying on stored energy

I've said this before, but if you compare the leafing out behavior to say a Japanese maple, the Japanese maple will slow down its leafing out proportional to its root loss. Maples likely store more energy in the trunk and they certainly regenerate roots faster than persimmon.

 

[NaoTK]

I'm still eating lunch and made a graph



I've also had this happen:


The 2nd graph here explains why good bud formation is a good predictor of health the next year. Large, fully-formed buds should be visible by October. If not, beware.

 

[Eric Schrader]

I'm not sure I've ever seen a graph in the literature that includes the term "The Valley of Suck".