Reducing top of Root Ball

[MrG]

Removing excess soil from the surface can be done any time. The feeder roots that provide feed and water for the tree are down in the pot and won't be affected by scraping away some surface soil.
You may uncover a few feeder roots as you work down but there should be more than enough down deeper - unless your recent repot was really severe.
Uncovering the thicker roots does not affect them or the tree. Thick roots are akin to a branch above ground. It's only a conduit from root tips to leaves. Thicker roots are also covered with bark. When exposed to air the bark will harden and be exactly like bark on the trunk.

If you feel you've gone far enough you can stop at any time and leave the tree to adjust then come back and go further when the tree and roots have adjusted to the new soil level. Exposed feeder roots will die off as they dry out but the tree will compensate by growing more deeper in the soil.

The scenario mentioned by @yashu where deer roots have grown upward to colonise the upper soil is a case where you may need to work in stages or do a full repot to try to work out which roots to bend down and which to cut entirely.
Need to treat each species according to how well they respond to root pruning.

IMHO that pine shown above is a bit high in the pot. I prefer to see trees actually planted IN the pot rather than above the pot.

This is really excellent - thank you for the insights @Shibui . I was wondering about these exact concepts so in a more wholistic view you have helped me analyze how to proceed.

And yes totally understood on the height of the other tree. I can see there is a degree of preference at play here as opposed to just right or wrong for the tree.

I’ve just spent some time removing excess top soil and surface roots and I’m seeing that a good 1/4” to 1/2” of the height was due to my top dressing - lesson learned. Photo attached in case it adds any value.

All best,
Mark

 

[MrG]

One more question potentially to fully flesh out this line of discussion:

What about fine feeder roots coming from the nebari? Should these be left to dry out or survive on their own, trimmed back, or carefully covered? It seems they’re sort of collateral damage for uncovering the nebari.




And to answer a question from earlier, I am realizing that I do prefer a more exposed root style overall.

All best,
MG

 

[bwaynef]

What you've exposed will toughen up or die. I wouldn't go to any effort to protect it.

 

[Shibui]

Those fine feeders are the reason most advice is to cover the roots.
In time many of the fine roots will grow and thicken to contribute to the nebari if they get a chance.

What about fine feeder roots coming from the nebari? Should these be left to dry out or survive on their own, trimmed back, or carefully covered?

It all depends what your vision for the tree and root system is:
If you're happy with the current thicker roots you can leave them uncovered. Most of the small ones will die as they dry out but you don't want them so no problem. I don't bother to cut them off. Nature will do that for me.
If you think the tree needs some more thick roots around the trunk you should cover them up now to encourage some or all to grow. It may take 5 -10 years for them to thicken but may be worth the wait. You'd probably need to do some selective root removal as they grow to produce the best looking nebari.

 

[leatherback]

I normally leave the full nebari covered up for as long as possible, and as a result most of my trees are in deeper pots. Over time I believe this creates better bonsai as you get these your roots filling gaps and you have more options to redu,ce less appealing worm roots, roots without taper or branching. So I clearly cover those.

Remember, in the end ideally we work towards roots that have the same characteristics as the branches, with taper, branching and movement and slowly disappear in the substrate.

 

[MrG]

Those fine feeders are the reason most advice is to cover the roots.
In time many of the fine roots will grow and thicken to contribute to the nebari if they get a chance.

It all depends what your vision for the tree and root system is:
If you're happy with the current thicker roots you can leave them uncovered. Most of the small ones will die as they dry out but you don't want them so no problem. I don't bother to cut them off. Nature will do that for me.
If you think the tree needs some more thick roots around the trunk you should cover them up now to encourage some or all to grow. It may take 5 -10 years for them to thicken but may be worth the wait. You'd probably need to do some selective root removal as they grow to produce the best looking nebari.

Thanks again everyone!

Last question on this: so for those fine feeder roots from the nebari, will those strictly grow to be bigger roots of their own, or will they contribute to the thickness/growth of the existing larger roots, or a little of both?

If I were to cover them but not want to cover them with thicker substrate, would a good option be to cover them with Kiryu, or spaghnum/moss blend? Or what’s best?

Thanks,
M

 

[leatherback]

Thanks again everyone!

Last question on this: so for those fine feeder roots from the nebari, will those strictly grow to be bigger roots of their own, or will they contribute to the thickness/growth of the existing larger roots, or a little of both?

If I were to cover them but not want to cover them with thicker substrate, would a good option be to cover them with Kiryu, or spaghnum/moss blend? Or what’s best?

Thanks,
M

With proper care, which includes regular trimming of the roots in the rootball, these smaller roots near the trunk will start extending and become bigger roots of their own.

I think it is best to decide for yourself if you aim for a long-term potentially better nebari, or short term beauty. In my view many people are too quick in wanting to get something in a small pot.

 

[pandacular]

I definitely hear you on enjoying the look of a tree with a bit more mound than what is commonly seen, but come to think of it, I think I only like it on bunjin (like the one you posted) and in particular in round pots. In other words, it has to fit the composition.

As roots grow, they will push up the top of the soil. This is known as soil heave and it can be used as an indicator of age. It is likely that the bunjin pine you posted has a mound partially due to soil heave, as old pines are often not repotted for quite a few years.

I like that you’re putting this much thought into it!

 

[Shibui]

Last question on this: so for those fine feeder roots from the nebari, will those strictly grow to be bigger roots of their own, or will they contribute to the thickness/growth of the existing larger roots, or a little of both?

Depends where each root is growing from.
All roots will thicken just as all branches above will thicken over time. Like branches root thickening seems to be in direct proportion to how much sap passes through so little roots will thicken slowly until they grow enough to start really pumping stuff up to the branches. Often a larger root will have a more defined link to a strong branch directly above and both will thicken faster than others nearby.
Roots coming direct from the trunk do not contribute to other roots but do add to the trunk thickening and trunk basal flare. The more roots you have growing directly from the trunk the more the trunk will buttress out.
Roots that are connected to other roots will contribute to thickening of those roots, just as secondary branches contribute to the branches they are connected to.

It is all about sap and nutrient flow. The more that passes through a particular spot, the more wood is generated there and the thicker that part gets.