When should I check them roots?

[James W.]

I have several root-over-rock I have started in the last 5 or so years. Juniper, Chinese elm, trident, JBP, mugo, cotoneaster, rosemary. My question, how long should I wait to dig one up and check the roots? I do not want to wait until the roots are not fixable, but I am afraid too quickly or too often will slow down development or kill a tree.
For example:
A Chinese elm was dug spring 2018 and roots trimmed, retied, etc. and planted back into the ground. The trunk has now grown out and needs to be chopped again. I'm thinking dig, chop, replant.
Juniper "Green Sea" has been in the ground on its rock since spring 2016 and only just last summer has started growing well. If I remember correctly it's on an ugly rock, might ought to dig it just to check and maybe not waste too much more time on it. On the other hand I would hate to kill it for no reason except my impatience.
Several small JBP, tridents and Chinese elms were tied to rocks and set into pots last spring and are ready to really get to growing this year. They are still pencil thin, but i would hate to let the roots get completely out of control.
What think you?

 

[Leo in N E Illinois]

Check too soon, you will disrupt the growth and slow down the process. A good sign is when you see the tree has actually grown. I think the elm is ready, if it grew enough for major pruning it is time to check the roots The juniper should probably be checked also, though that one could probably wait until next spring, hence 2 seasons of good growth. The little ones, you want at least 2 seasons with good growth to allow roots to develop. Pine roots just like pine branches, stay somewhat flexible for quite a number of years.

 

[James W.]

Check too soon, you will disrupt the growth and slow down the process. A good sign is when you see the tree has actually grown. I think the elm is ready, if it grew enough for major pruning it is time to check the roots The juniper should probably be checked also, though that one could probably wait until next spring, hence 2 seasons of good growth. The little ones, you want at least 2 seasons with good growth to allow roots to develop. Pine roots just like pine branches, stay somewhat flexible for quite a number of years.

Thank you, that was my inclination.
I have a handful of mugos that will get checked this spring. @Vance Wood ? maybe wait until June? they will have to be basically bare rooted (but not washed).

 

[Shibui]

I check my trident root over rocks every winter. They grow fast here and so do the roots. Tridents have the tendency to put out new lateral roots just under the ground. When one of those takes off it can permanently ruin the whole arrangement. As tridents prefer to have surface roots the deep roots wrapped on the rock often stop growing in favour of new laterals. Again your work is ruined. Annual inspection can stop problems before they get too bad. I do not see disruption to growth with annual dig, prune and rearrange roots.

Other species do not suffer the same problems but I still like to check that the roots are still growing as I intended, at least until the roots are set enough that they won't move while being reburied.
Both junipers and pines are slow to get going. It can take 3-5 years before there is significant growth in my grow beds so they tend to stay untouched for a number of years at a time.

I have no problem brushing the soil off pine roots. They soon get growing again after being replanted.