Double Trunk Cork Oak

[symbiotic1]

At the Bonsai-a-thon I picked up a nice cork oak from a vendor there called Legacy Cork Oaks. Here's a poor quality image of it for now, I'll post more detail shots tomorrow.

Besides starting this thread as a progression thread, I had a question that came up when I was repotting it today into more open soil and a wider pot. As I was bare rooting the tree I wondered how much of the root ball should I have taken off? This is only my first year of doing bare rooting of trees and also the first doing some on my own, so I'm guessing I was probably too conservative in my chopping. The tree is already leafing out and I didn't want to shock it too much.

I'm curious how much of this root ball you more experienced folk would have lobbed off.


I had only taken off about an inch or so of the rootball in these shots. Should I have gone further? To qualify that question: I'm currently just wanting the tree to keep growing vigorously and not trying to shrink the root ball for a bonsai pot for a few years at least. It may go into the ground next year if I have a more permanent place to plant it but for now it's in a pot.

 

[sorce]

Though California oaks seem a little more robust, I've read to go easy on oak roots.

Seems good to me.

But did you work them nice for the future planting?

Sorce

 

[markyscott]

The problem is that there are many thick roots growing downward. If this is to ever be a bonsai, the root system needs to be growing parallel to the soil level and it should be relatively flat. Right now it looks as though there are large roots growing down that are maybe 10" deep. Others appear to be long and are circling the tree. Neither have any future in your tree and need to be eliminated, eventually. Both are probably the result of living in a nursery can for a long time. So working the roots, to me, would mean working the rootball toward the eventual goal of something a couple of inches deep, flat, and with roots radiating from the trunk. What's your plan for getting it out of the nursery can and into a bonsai pot one day?

Scott

 

[JudyB]

I did a pretty radical chop of a rootball on a cork oak, just at bud push a couple years ago. The tree never skipped a beat. And I did do the flat cut and right into a pot. So you might be ok, but a little late in doing this.
To me this looks like two trees that are growing next to each other with an entangled root system, than a twin trunk tree. I would cut them apart and grow separately if that's the case, as it will probably always appear that way. Unless it's joined lower than I can see.

 

[symbiotic1]

Thanks for the replies. There are some thick roots growing downward, almost like a big thick root bulb as well in there. I guess I erred on the side of caution this time because the tree has a lot of new growing pushing out and the only pruning I did to the top was to remove a branch I knew had to go. I combed the roots out somewhat but now I'm guessing I should have gone further on that.

My main goal right now is to get the two trunks to fuse into one large base, which they are already starting to do just at the soil line. There is a sort of semi hollow shape on what I've tagged as the front of the tree that could look interesting as the trunks fuse. I envision this eventually looking like a massive, sprawling oak and want to train the branching to arc and hang down as though it's a very old tree with thick heavy branches.






As for a plan for training the roots, I figured leaving more roots might be a benefit in moving from the potting soil it was in to the rocky new soil - more roots to absorb less moisture (just a shot-in-the-dark guess there)? The bottom of the pot I took it from was soggy muck with no roots despite not being watered in several days. Again at this point I was more concerned about protecting the new growth. Even now in the pics the new shoots are looking wilted. It's warm and windy right now so everything is drying out fast. Hopefully the new soil will encourage new roots higher up. Then in a year or two should I start reducing the large downwards roots one by one or just go all-in and do a hard pruning on them?

 

[milehigh_7]

Oaks generally do not do well with hard root pruning and if done should be done just as new leaves are pushing. Keep us posted on how it does. I would totally let it rest for a year or even two.

 

[ColinFraser]

To me this looks like two trees that are growing next to each other with an entangled root system, than a twin trunk tree. I would cut them apart and grow separately if that's the case, as it will probably always appear that way. Unless it's joined lower than I can see.

My initial thought was the same as Judy's. Can you post a closeup of how they are joined? Someone with more experience will probably chime in, but it doesn't seem to me like there is really enough trunk contact to get any kind of fusion higher up . . . with the caveat that many things are possible with inordinate amounts of time.

I like the look of the trunk on the right in the very first photo. It looks like it could already be on its way to 'oak style' or some similar 'informal broom' type of shape.

Have fun; I know I am! I'm off work today because my throat is too sore to speak, but I can still fuss with my trees . . . and I don't have to talk to them (it's optional, unless you have one of those "deaf myrtles" mentioned in another thread).

 

[markyscott]

It'll do better with a better draining soil.

But you'll still need to eventually remove those ginormous downward growing roots. theyll just get worse over time. You'll have to do it in stages - you may not want to lop off all the roots in one go. Best to have a plan. You'll want some fine feeder roots at the base, ready to take over when your ready to cut back the big roots.

So what are the choices?

1. You could layer the tree and start over clean with a new set of roots
2. You could graft new roots at the base and then cut back
3. You could cut back a bit at a time and hope new roots come out where you want them

You missed the opportunity to do 2 or 3 this time and it's probably best not to pull it out of the pot again. So it seems as though your choice is to layer it at wait until next year to either graft or start cutting back.

I usually wait two years to separate the root grafts. So that, or cutting back a root or two at a time will be a multi year process.

Maybe layering is the way to go?

What do you think?

Scott

 

[milehigh_7]

It'll do better with a better draining soil.

But you'll still need to eventually remove those ginormous downward growing roots. theyll just get worse over time. You'll have to do it in stages - you may not want to lop off all the roots in one go. Best to have a plan. You'll want some fine feeder roots at the base, ready to take over when your ready to cut back the big roots.

So what are the choices?

1. You could layer the tree and start over clean with a new set of roots

Maybe layering is the way to go?

What do you think?

Scott

I think you would be better off to buy another tree than try to layer an oak. It can be done but not the best option by far.

Yes you need a plan but a well informed plan. Oak roots can't be done quickly. If it works you were lucky.

My suggestion is to let it rest this year and spend this time finding a few people with experience with this species. Then develop a plan. Like I said only do roots just as the buds are beginning to move. The top will grow like mad more than likely.

 

[markyscott]

Rob's right. Oak roots are difficult to correct.

For help, you might try George Muranaka - he grows them and might be able to guide you as you think through what to do next. He at least reports trying to air layer them on his blog.

http://muranakabonsainursery.blogspot.com/2012/05/large-cork-oak-air-layers.html

But I've never tried.

I have grafted roots on collected southern live oak, and Ive had good luck with that. But every time I repot, I spend a lot of time grafting and reducing big roots (some as big around as my arm - not fun to cut).

Anyway, just give it some thought before your next repot - they take time to fix.

Scott

 

[symbiotic1]

Thanks again for the replies. This gives me a few things to think about in making a plan for the tree. The nursery I take classes from grows these oaks so I could form a plan with him. Also the tree's grower lives less than an hour away so I'll see how or if he has handled reducing the roots. This guy mainly grows only cork oaks. Good to know George grows them too so there are a few resources around to ask.

If anything I've learned anything so far from BNut it's the advantages of good draining soil so that was my first step. The soil depth of the new pot is an inch or two more shallow than the one before it, and about 5 inches wider, so here's hoping it may try spreading the roots out instead of going any further down.

I've heard of scoring the roots or base of the trunk to encourage root growth, do oaks respond well to this?

The thought also came to mind of trying to gradually expose more of the trunk by gradually removing top soil over time to harden off the surface roots and help form some nebari similar to removing soil gradually with a root over rock. The larger roots don't begin until at least and inch or two below the new soil line. Could this be done to sort of reduce the below soil root mass from both directions?

I really appreciate the advice so far, everyone. I had an inkling their roots were somewhat touchy so this confirms it. For now it's a waiting game to see how it reacts to what I've done so far.

 

[JudyB]

I would consider at least thinking about separating the two trunks. They just don't read as one tree at all to me. For this year, just let it grow, course you already know that. I would send a PM to PaulH, our resident oak expert, if anyone on this board can help you, it's him.

 

[Bonsai Nut]

One thing to watch... these things cork out like mad. You really have to watch your taper and trunk lines. You start with an interesting curvy trunk and in 3 years you have a stove pipe because the corking bark tends to fill everything in. Branches get too thick, etc.

 

[symbiotic1]

One thing to watch... these things cork out like mad. You really have to watch your taper and trunk lines. You start with an interesting curvy trunk and in 3 years you have a stove pipe because the corking bark tends to fill everything in. Branches get too thick, etc.

How does one combat this tendency then? Do you create more extreme taper in the trunk and branches by letting things grow longer before chopping them back to one or two buds?

 

[milehigh_7]

I would consider at least thinking about separating the two trunks. They just don't read as one tree at all to me. For this year, just let it grow, course you already know that. I would send a PM to PaulH, our resident oak expert, if anyone on this board can help you, it's him.

+1 in talking to Paul, BNut does oaks and I reached out to Mauro Stemberger a few years ago and he is amazing. Very humble, helpful and very very talented. He is on facebook.

 

[Bonsai Nut]

How does one combat this tendency then? Do you create more extreme taper in the trunk and branches by letting things grow longer before chopping them back to one or two buds?

You have to be overemphasize everything in your trunk design. Have you ever roasted marshmallows over a fire, and they puff up and get formless? That is exactly what these trunks will do. You have to plan for 90 degree bends in the trunk, and when it corks up it will look good. You would normally not want to be so extreme with other trees.

 

[symbiotic1]

Interesting. Never thought about that the good corking has a downside if not planned correctly. I guess that may mean I'd have to chop off most of the left trunk otherwise it will quickly lose its movement. It doesn't have much taper in it anyway. Ill study it more and draw up some design ideas to see where best to chop. I'm guessing wait at least until the new growth hardens off or until dormancy before thinking of chopping?

 

[Bonsai Nut]

Do NOT do anything drastic in the mid or late summer. I have trimmed too late in the season and gotten bad die-back before. I have gotten best results at end of dormancy or right when buds are popping.

And before you chop - consider air-layering. These are really fun trees that develop very quickly.

 

[symbiotic1]

Good idea. I'd be happy to try to layer it but got the impression from earlier responses and Muranaka's blog that these oaks were difficult to do that to. In his blog article it looked like he attempted his layer in May. Should I wait until next year to start to layer it or should I just go for it this year if the tree seems to be growing well in the next couple months?

 

[barely]

Hi,
Just came across this thread. My name is Barry Altshule from Legacy Cork Oaks and I am the person from whom you bought this tree at the Bonsai a thon. I really appreciate all the work and care you have put into this cork oak. If you would like to discuss your tree in detail, please call me at 626 826 6250.