Will roots grow from a thick root thats been pruned back?

[FiggieSmalls]

Feels like a pretty noob question here! I'm wondering what happens when a thick root is pruned back to where it is just a stub of an inch or two in length? Will more roots grow from the cut end, or further back? Or will the root just die in all likelihood?

Thanks!
Figgie

 

[dbonsaiw]

the short answer is yes. In fact, that’s how we get the roots to ramify.

 

[Shibui]

I find that more than 90% of new roots grow direct from the exposed cambium of the cut ends of roots so if I want roots to divide and ramify I know to chop the roots at that spot rather than cut long and hope for roots to grow back along the length of the root.

There could be some differences between species. I have more experience with deciduous but from what I can see JBP roots respond very similar.

Chopping thick roots to short stubs is not a good idea on all species. Trident maples, most apples, privet, banksia, most ficus and some others can have roots chopped hard. I often make initial root chops on tridents so that the roots are similar length to the trunk diameter.
Junipers and pine roots can't be chopped that hard. They will often die if all the roots are chopped back to stubs.
There's a whole range of species that have in between tolerance for root trimming.
Knowing which can be chopped hard and which don't do well is from experience or research. If in doubt, err on the side of caution and leave extra root just in case.

 

[johng]

I find that more than 90% of new roots grow direct from the exposed cambium of the cut ends of roots so if I want roots to divide and ramify I know to chop the roots at that spot rather than cut long and hope for roots to grow back along the length of the root.

There could be some differences between species. I have more experience with deciduous but from what I can see JBP roots respond very similar.

Chopping thick roots to short stubs is not a good idea on all species. Trident maples, most apples, privet, banksia, most ficus and some others can have roots chopped hard. I often make initial root chops on tridents so that the roots are similar length to the trunk diameter.
Junipers and pine roots can't be chopped that hard. They will often die if all the roots are chopped back to stubs.
There's a whole range of species that have in between tolerance for root trimming.
Knowing which can be chopped hard and which don't do well is from experience or research. If in doubt, err on the side of caution and leave extra root just in case.

Very good advice!! As usual!!

 

[rockm]

Roots ramify just like the tops of bonsai. Same principle for the most part--cut back get more growth from wound site as the tree replaces what been removed. As said above, this capability varies among species. Most deciduous trees rapidly regenerate new denser feeder roots from older, less efficient roots. Larger diameter roots are older growth and less effective at getting nutrients and moisture from the soil. They are "transport" pipelines for the feeder roots at their ends. Shortening them forces a "replumbing" of the system, forcing more effective, efficient and localized root system that works in the confined space of a pot.