Juniper Pro Nana repotting questions

[Jupiter]

Hey, I have a Juniper procumbens nana in a pot, that I am looking at repotting soon. It was purchased from a garden center and is in pretty good shape for the time that I've had it. The soil mixture seems to be a little too water retentive and i have a mix of lava rock, haydite and conifer bark ready to go in the pot. I have seen soo many different opinions of how to go about repotting junipers that it has lead to a lot of confusion on my part. Obviously having the old soil replaced with the new soil as quickly as possible is the goal, but I am not looking at adding this tree to the death count yet. should I bare root or HBR? Should I make sure to mix some of the old soil in with the new mix? It is still a young tree so is it likely it will survive the repot with ease? Should I wait for a better time or will now be ok? I live in Ontario Canada zone 5A. Any information is greatly appreciated along with any tips and tricks you might have for additional success!!!

 

[lehigh4me]

I just repotted 7 Procumbens Nanas, but did not bare root. Just pruned a little lowered the soil level to show the trunk a little better. I live in Iowa which is Zone 5. I used mixed in some calcined clay to make it drain a little faster and used a little of the old pine bark soil mixed in. I am keeping my fingers crossed lol.

 

[Wires_Guy_wires]

Whats the season in Ontario at the moment?
Fall and spring are the best seasons to repot, a month before freezing conditions in fall or a week or so after in spring.
Hbr is safe, but I like knocking off most of the soil gently without damaging the roots. Procumbens can do pretty well if you leave parts of the old soil and replace the outer soil. Assess what the roots look like when you take it out of the container; if there are a lot of white roots, you can be more aggressive with removing the old soil. If there isn't a lot of white fresh root growth, it's weaker and you'll have to be more gentle.
As long as you don't cut those roots, it'll probably be fine.

 

[Shibui]

It is now spring in my area and I am repotting junipers now. I routinely remove as much old soil as I can at repotting though most of mine have been grown in my standard mix so don't really require total bare root.
Young junipers have no problem with bare root or even with extensive root pruning.
Why would I want to keep sub-standard soil around the roots of a tree if I thought that soil would harm the tree?
I know there are a range of opinions and methods for most bonsai operations. That confused me for a while too until I realized that none of those approaches are totally wrong. They all work for those who use them. Despite those who would have us believe that theirs is the one and only safe method you will probably be OK using any of the modified methods.

 

[Japonicus]

freezing conditions in fall or a week or so after in spring.

@Jupiter I like this this strategy, just don't go freely removing foliage or thinning at all
beginning now, until it has recovered from next Springs potting up. Like July-August,
thinning would be ok if foliage is active and robust.

I would cut roots back 60% from the bottom and rake out laterally what is left somewhat,
keeping old soil in the crown of the roots mostly. (Just under the trunk maybe 30% of total root mass now).
When you remove 60% from the bottom, then rake from the bottom center out mostly, then some on top,
addressing poorly placed roots, you will be removing approximately 70-75% overall. Then address more with
each subsequent repot. Works for me.

Here's a "for instance" example with a hinoki, but it is a repot, not initial potting up...

Notice I let the soil dry 1st to prevent damage to the roots when working them.
At this point the roots do not tear as easily. Good policy prior to wiring as well.

Here's a juniper from nursery can to pot...

I don't see a lot of white roots, but it was and still is very robust.
I would not recommend to you, to remove 75% right off the bat though
and then start combing out. 50-60% is safer.