When to repot / do root work on Liquidambar?

[TimIAm]

I have about a dozen liquidambar in a grow bed. I am trying to find out when is the best time to remove them from the grow bed and do some root work?

As I'm in Australia, we are getting close to repotting time for most species. Where I am in Sydney, looking at my trees, I'd say I have a week before new leaves start coming out.

So should I be taking them out now (before new leaves emerge)? Immediately after new leaves emerge, or when new growth hardens off?

These are L. styraciflua

 

[baldone]

Bonsai South | Better Material Means Better Bonsai

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Zach Smith knows them very well, just compare our zones to yours for temps and times.

 

[Wulfskaar]

I think when the buds are swelling but the leaves have yet to emerge is a good time.