New young zelkova, too late to repot?

baron

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Hi,

I recently got two lovely new little trees. A field maple and a zelkova nire. Both young trees, so I'm not quite sure yet what to do with them
When I got them the buds were swelling on both so I decided to take advantage and repotted the maple first. (https://bonsainut.com/threads/new-field-maple.33015/)

Now those buds starting to move a little, but the zelkova seems to be a lot more vigorous and I haven't had time/supplies/soil yet to repot that one :confused:
Should I just leave it there, do some maintenance pruning and repot next spring? Or would it be better to slippot it into a grow box/colander/bigger pot?
I have no idea what kind of soil its currently in...seems mostly organic.
 

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Bonsai Nut

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I would first pop it out of that plastic pot and inspect the roots. If the soil is still pretty open and the roots are not crowding the inner circumference of the pot, you are probably fine to wait a year. If the tree is root-bound, you really need to take action.

You still have several weeks if not a month or so to repot. Can't you scare up supplies in the next couple of weeks?
 

baron

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I'm afraid it's pretty root bound :( I'll take some pictures tomorrow.
If I have a couple of weeks I can yes, just thought I was already too late
 

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I'm afraid it's pretty root bound :( I'll take some pictures tomorrow.
If I have a couple of weeks I can yes, just thought I was already too late
With deciduous trees, particularly strong ones like elms and zelkovas, you have more latitude in terms of repotting time. You have a window when the buds are swelling but before they push leaves. Then you need to wait until they push their first round of growth and it hardens. Then you have a second window to repot. The key is that you want the tree well established before the heat of the summer.

As with everything bonsai "it depends" on many things. If you are only going to remove the old soil and repot the tree (without root pruning) it is much less stressful on the tree and you have more latitude with timing. But the stress of repotting a rootbound tree is much less than leaving it in a rootbound condition for another year...
 

baron

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Ok! Thank you for the confirmation I needed :)
I'm guessing a growbox would be best/easiest for a slip pot and this being a very young tree?
 

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Ok! Thank you for the confirmation I needed :)
I'm guessing a growbox would be best/easiest for a slip pot and this being a very young tree?
I wouldn't recommend slip-potting a root-bound tree. You are just asking for trouble. Think about it this way - many times a root-bound tree has been slip-potted several times, particularly if it is from a commercial nursery. Each time a new layer of roots and soil is added around the old layer of roots and soil. It is like a snowball that is just getting thicker. Meanwhile the inner core of the ball is getting more and more difficult to get water and air into. It has a tendency to stay wet - and rot - or stay dry - and all the inner fine roots die.

Far better to gently tease out the roots, even if you will inadvertently break some or bruise some, and leave the tree with all new soil. Elms can take it. You don't have to have perfect roots the first year - just focus on getting them laid out in good soil in a somewhat horizontal plane. Next year you can repot again and get a little more aggressive - because your tree will be 10x as strong.
 
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Bonsai Nut

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I always have to be careful when I throw out guidelines as if they affect everyone everywhere equally. For me, almost all my trees hunker down in the summer. Nothing is pushing new growth in July - because it would burn up. All my deciduous are calloused up under shade cloth, and even my pines are in suspended animation.

Then again, I don't know too many places that can do two candle prunings on black pines in one season - because pines here have two growth seasons - spring and fall.
 

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All my deciduous are calloused up under shade cloth, and even my pines are in suspended animation.
I think this cherished 'knowledge' should be questioned. I think you will find they aren't so 'dormant'. They simply are NOT EXTENDING new growth. The average heat in Orange Co is 'hot', but I don't think too hot.

Knowns are that
  • enzymatic reactions increase with temperature (carbon/energy loss)
  • metabolic reactions increase with temperature (carbon/energy loss)
  • the rate of photosynthesis increases with temperature (carbon/energy gain) up to 95F/35C
    • refresh of the RuBisCo enzyme tops out.
  • oxygen diffuses more rapidly in water the higher the temperature
  • the amount of oxygen dissolved in water decreases with increasing temperature.
In other words, trees are indeed growing (carbon accumulating) during the day, when the temperature is below 95/35C! Root growth peaks at some lower temperature (oxygen limited), near 72F/25C which can be occur overnight or be affected by watering and/or shading of the pot (stick a meat thermometer in there and find out). So, it is quite possible that your trees could recover very quickly when repotted 'in the heat of summer'. One has just gotta get brave enough to attentively try it (as opposed to 'knowing' it cannot be done).
 

baron

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Thnx for the many answers!
@0soyoung I haven't had time yet to read the entire experiment yet, but following your conclusions: August/September repotting would also be possible, but a spring repot is still the safer choice?
I was also under the impression when you repot during spring the roots have more time to develop and prepare for winter/frosts?

The pictures I said I would take..
 

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Thnx for the many answers!
@0soyoung I haven't had time yet to read the entire experiment yet, but following your conclusions: August/September repotting would also be possible, but a spring repot is still the safer choice?
I was also under the impression when you repot during spring the roots have more time to develop and prepare for winter/frosts?
I have continued to repot half of these experiment zelkovas in spring and half in Aug/Sep and have no sense of one time is inherently any better than the other. The obvious risk repotting broadleafed trees in summer is desiccation. I indeed saw some persistent loss of turgidity repotting eastern redbuds in Aug/Sep. However, I did not see any sort of problem with repotting waxy broadleaf species like zelkova and cork oaks in Aug/Sep. Azaleas, rhododendrons, pyracanthas, quince, hollies (ilex), and roses can certainly be added to this list of 'waxy leafed angiosperms' that can be repotted after the summer solstice.

With the passage of time, I've become convinced that repotting/digging after the summer solstice is safer than spring with many species, particularly flowering ones. I killed a lot of quince trying to repot them after flowering. Repotting before flowering is safer, but it is just too easy to knock off the flower buds! Life is EZPZ repotting them after the summer solstice. But, I am just an amateur gardening hack trying to make bonsai. I've got more than 100 trees in various states of 'development'. I am motivated to spread out the workload and not be overwhelmed by 'repotting season'. I habitually repot my maples in spring 'as buds swell, but it is not a hard rule for me. I tend to repot conifers, azaleas, quince in Aug/Sep. But I also use spring verus Aug/Sep interchangeably. Sometimes I find a pot for a tree and just don't want to wait until spring (or Aug/Sep) - I put it in that new pot in Aug/Sep. (or spring) for instance. I've even gone so far as to half bare root a JBP in spring and again in Aug/Sep (and vice versa) which saved me a year getting them out of nursery soil. I've done likewise with a tsuga Canadensis.

As to winter hardening, this occurs because of the pattern of deepening overnight frosts and daily thaws that are characteristic of fall. Trees reduce the water in living tissues and sugar up to resist freezing. We're also told that roots continue to grow in winter as long as their temperature is above 40F/5C. So, it is not clear to me why newly pruned roots would be any more cold sensitive than unpruned ones, but there are abundant anecdotes from commercial growers about them being more vulnerable to sudden hard freezes - they cite higher survival rates for roots that hadn't been disturbed about 6 weeks or more earlier. It is an interesting thing, but I live in a climate very similar to yours and have no means to investigate it. Were I living in the mountains of Colorado (e.g., Steamboat Springs where the first frost can occur in Aug/Sep), for example, I very well would.
 
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baron

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Very interesting read for sure! Unfortunately I already did all my repots so can't put it to the test this year. Altho I might have a test subject in mind... I have this spruce that was repotted, but the pot is actually too small..
Next year I'll try and do my Azaleas and rhododendrons after the summer solstice. For now I'm good and only have 13 trees so repotting during spring is manageable.
I can see how having 100+ trees makes you try and spread out the workload tho :D

@Bonsai Nut, I managed to pull some soil mix together, It's not ideal (bit too much akadama), but it will do for now so I went ahead and did the repot now.
I should've placed it a little bit more off-center to compensate for the slanting but will fix that next year or in 2 years.
 

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baron

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This one grew fine over the past months and becoming a mess of little twigs so I did some light pruning and wiring to open it up more so it can get bigger next year.
I'm also trying to adjust the angle of the main trunk and go for a new front.

Before (sorry dark pics)
IMG_9449.JPG IMG_9448.JPG IMG_9447.JPG IMG_9446.JPG

After

IMG_9459.JPG IMG_9458.JPG IMG_9457.JPG IMG_9456.JPG
 

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