Best Species of Carpinus?

[Gabler]

There are many species of Carpinus used for bonsai. Which is your favorite and why? Please share other species you have worked with, so we have a basis for comparison.

I have worked only with Carpinus caroliniana, so I cannot extol its merits. I have no idea how it compares to other species in the genus.

Pic for attention:

 

[rockm]

Carpinus Coreana/turcaninovii. Smallest leaves of most any hornbeam. Leaves are Small initially and reduce even more. Capable of Dense heavy ramification. Can produce very fine fall color with orange and red. Drawback is slow healing on chops and some (extreme) sun sensitivity. Also not very many mature large trunked stock or specimens tree are easily available in the U.S. for reasonable money.

Carpinus caroliniana leaf reduction and ramification pales in comparison.

 

[Gabler]

Carpinus Coreana/turcaninovii. Smallest leaves of most any hornbeam. Leaves are Small initially and reduce even more. Capable of Dense heavy ramification. Can produce very fine fall color with orange and red. Drawback is slow healing on chops and some (extreme) sun sensitivity. Also not very many mature large trunked stock or specimens tree are easily available in the U.S. for reasonable money.

Carpinus caroliniana leaf reduction and ramification pales in comparison.

I grow my Carolina hornbeam in full sun. It reduces leaf size and internode length while promoting more red in the fall leaf color. I take it this would be a bad strategy if I ever find myself in possession of a Korean Hornbeam?

 

[rockm]

I grow my Carolina hornbeam in full sun. It reduces leaf size and internode length while promoting more red in the fall leaf color. I take it this would be a bad strategy if I ever find myself in possession of a Korean Hornbeam?

Maybe maybe not. Can depend on soil/root temps

over the years I’ve become more middle of the road in recommending Carolina Hornbeam as bonsai material. It becomes less root hardy once containerized and can suddenly give up the ghost or suffer dieback after particularly harsh winters. Additionally big trunk chops may never heal. Ramification is never really terrific and leaves reduce but not to 1/4 - 1/8 inch

It’s a good species though-readily available and extremely easy to collect. Behaves enough to make really really good bonsai

If I had similar sized Korean and Carolina hornbeam offered to me I’d opt for the Korean tree though.

 

[Gabler]

I have effectively a limitless supply of C. caroliniana in the swamp behind my parents' house, so I have not bothered to spend any money on other species. I would also consider their roots to be unusually cold hardy, even in a very shallow pot. That being said, I find they respond poorly to pinching, so I take an approach closer to Walter Pall's hedge pruning method (albeit more intentional about which twigs I'm pruning and by how much).

 

[DeepSouth]

I too have a limitless supply of C. caroliniana on our private land. I have collected several and am planning to collect a couple this Spring.

But honestly, I have some qualms with them, namely the following:

1. They don't heal over trunk chops very well at all. In larger specimens that I have seen in professional bonsai gardens around the US, the trunk chops are typically carved. Small tress (less than 2") seem to be able to heal OK. In the oldest specimens that I have seen, the heartwood is often missing entirely after rotting away. This can create a pretty cool effect, in my opinion, but it certainly would not be appealing to the eyes of someone who prefers the traditional Japanese style deciduous.
2. The bark and cambium layer is incredibly thin. It's like paper. If you accidentally poke it with anything remotely sharp, chances are that you went all the way through. Just scratching the bark seems to remove the whole cambium.
3. New shoots are super brittle.
4. They are fairly prone to fungus although it is very easy to manage compared to other species so not really an issue.

My favorite, although not technically Carpinus, is Ostrya virginiana. It is very closely related to Carpinus. I have not had any of the afforementioned issue with it. The only negatives compared to C. caroliniana that I have experienced are that it grows a little bit slower and the branches are stiffer, making them difficult to wire after they have hardened.

I have not tried Korean hornbeam, but from what I have been told, they are a very good species to work with.

 

[Gabler]

I too have a limitless supply of C. caroliniana on our private land. I have collected several and am planning to collect a couple this Spring.

But honestly, I have some qualms with them, namely the following:

1. They don't heal over trunk chops very well at all. In larger specimens that I have seen in professional bonsai gardens around the US, the trunk chops are typically carved. Small tress (less than 2") seem to be able to heal OK. In the oldest specimens that I have seen, the heartwood is often missing entirely after rotting away. This can create a pretty cool effect, in my opinion, but it certainly would not be appealing to the eyes of someone who prefers the traditional Japanese style deciduous.
2. The bark and cambium layer is incredibly thin. It's like paper. If you accidentally poke it with anything remotely sharp, chances are that you went all the way through. Just scratching the bark seems to remove the whole cambium.
3. New shoots are super brittle.
4. They are fairly prone to fungus although it is very easy to manage compared to other species so not really an issue.

My favorite, although not technically Carpinus, is Ostrya virginiana. It is very closely related to Carpinus. I have not had any of the afforementioned issue with it. The only negatives compared to C. caroliniana that I have experienced are that it grows a little bit slower and the branches are stiffer, making them difficult to wire after they have hardened.

I have not tried Korean hornbeam, but from what I have been told, they are a very good species to work with.

1. It's my understanding that all Carpinus is reluctant to heal wounds. Would you say that C. caroliniana is uniquely bad? How does it compare with Ostrya virginiana?

2. I'm not sure why the thin bark would be a problem. It's never caused any issues for me.

3. There's a sweet spot where the new shoots have started to lignify but haven't fully hardened. If I need to wire a shoot, I wire it in that window. Otherwise, it's clip and grow for me. I prefer to clip and grow anyway.

4. I have not noticed any problems with mine, and I keep them fairly wet. It must be a regional thing. By contrast, I can't grow hawthorn at all, even with multiple fungicides in rotation.

5. Ostrya virginiana is not native to my area. It grows both north of me and south of me, but it eschews the Delmarva Peninsula, so I don't have a ready supply. Would it be worth my time to buy it, or should I just buy C. coreana instead?

 

[DeepSouth]

1. It's my understanding that all Carpinus is reluctant to heal wounds. Would you say that C. caroliniana is uniquely bad? How does it compare with Ostrya virginiana?

2. I'm not sure why the thin bark would be a problem. It's never caused any issues for me.

3. There's a sweet spot where the new shoots have started to lignify but haven't fully hardened. If I need to wire a shoot, I wire it in that window. Otherwise, it's clip and grow for me. I prefer to clip and grow anyway.

4. I have not noticed any problems with mine, and I keep them fairly wet. It must be a regional thing. By contrast, I can't grow hawthorn at all, even with multiple fungicides in rotation.

5. Ostrya virginiana is not native to my area. It grows both north of me and south of me, but it eschews the Delmarva Peninsula, so I don't have a ready supply. Would it be worth my time to buy it, or should I just buy C. coreana instead?

A lot of my experience with them probably comes down to environmental factors. Particularly the fungal issues. Our summers are near 100% humidity and very warm for months on end. And to be clear, it is still a good species to work with.

Regarding the wound healing, I have not worked with C. koreana or the C. betulus so I can't comment on those other than what I've observed. On a recent trip to Japan, I saw many beautiful specimens of C. koreana that had well-healed, large wounds that I have not seen before on C. caroliniana.

Ostrya virginiana heals more consistently than C. caroliniana, in my experience. Another plus is that their leaves reduce better.

Regarding whether you should choose C. koreana, C. caroliniana, or O. virginiana. If you want the species with the best qualities and resources for bonsai, C. koreana is your best bet. If you want a species that is native and easy to work with, I would try to find a source for O. virginiana. Zach Smith here in LA used to have them for sale every now and then, but he has retired.

I have also seen some beautiful specimens of Ostrya carpinifolia, the European hop-hornbeam, which look and behave similar to the species here in America.

 

[The Barber]

I have effectively a limitless supply of C. caroliniana in the swamp behind my parents' house, so I have not bothered to spend any money on other species. I would also consider their roots to be unusually cold hardy, even in a very shallow pot. That being said, I find they respond poorly to pinching, so I take an approach closer to Walter Pall's hedge pruning method (albeit more intentional about which twigs I'm pruning and by how much).

I find that so long as American hornbeam are super vigorous they respond pretty well to pinching. I managed to go from no branches to 4 branch pushes this year on one. Been using NPK-Grow on them weekly during the grow season and it has made a big difference.

This one is a good example. It didnt even have the best roots. Potted in an Anderson Flat in pure pumice, the medium coarse stuff, because I was out of any fine to mix in at the time. Thrown under 70 percent shade cloth where it still gets full morning and evening sun for a couple hours of each. 6ft leader and decent ramification for a year 1 collected tree I would say.

I wire the newer branches when they begin to elongate, and they hold form within 2 weeks, then unwire and prune at this time. It has been working for me, though some trees respond better than others.



Heres another one that did really well with the same methods and also lacked a crazy amount of roots at collection, dont have a photo of it after leaf drop, and it is too cold out for me to desire trudging out into this 20 degree weather.

At collection back in the spring. A mile hike out with 6 trees in tow and didnt want to pack all the soil, so it got bare rooted and soaked in the creek then wrapped in cellophane. Then i add water into the cellophane and the roots never dry out by the time i pot them.


And this is at the end of summer. Started the carving of the hollow, and added some more wire at that time.

 

[The Barber]

I would also add that I have mature C. Coreana, C. Turczaninovii, C. Caroliniana.
I have some younger C. Betulus, but haven't worked with them enough to offer any input.

I love all 3 species, but for their own reasons.

Pros and cons
C. Corrana
Pros
Smallest leaf reduction and tightest internodes of any Carpinus species. Shade tolerant. Least brittle of the Carpinus I have dealt with. They ramify nicely, at least for me.
Cons
Shin based tree (treat it like a pine at repot), major root removal may cause portions of the tree to die. Slow to heal wounds, if ever. They dislike full sun. Very slow to thicken, and old imports are very scarce.

C. Turczaninovii
Pros and cons
Only differs slightly from C. Coreana in that it has longer internodes, and leaves are a slightly different shape and a slightly larger leaf, the deadwood is extremely hard and long lasting on this species (not sure about C. Coreana in comparison)

C. Caroliniana
Pros
Unique "Muscular" fluted trunks (see photo below), which makes every one of these trees unique. Most winter hardy of the 3 in my opinion. More sun tolerant than the other 2.
Cons
Longer internodes. Larger leaves. Once hardened off, branches become quite brittle.

 

[Jcmmaple]

@The Barber i notice you only seal the outer ring, I have had serious die back on the few I collected from not sealing. What have been your experience to keep survival rate high?

 

[The Barber]

@The Barber i notice you only seal the outer ring, I have had serious die back on the few I collected from not sealing. What have been your experience to keep survival rate high?

I only did that for the tree I am going to let hollow out to help protect it and allow it to roll inward and protect the cambium layer. The rest get the orange Jin seal in the tube applied decently thick and I apply over the edge onto the bark slightly as to get a full seal. The putty never stays on long enough to keep me happy. I had the same issues of dieback when I didnt seal. Anything I cut off even slightly substantial gets sealed these days.