When can yamadori be worked?

Hi there!

I was wondering how long one has to wait before collected material can be worked? Of course the tree should be allowed to settle in and develop roots and shoots before hard pruning etc., but is it possible to bend some of the major branches in order to set the ‘bones’ of the material within e.g. the first half year of collection?

This is a good question. Each time we work a tree, we weaken the tree through stress and set back the normal growth or recovery pattern. Wiring and bending branches produce stress fractures while we are setting the bones. Healing the fractures sets the branches in position.
The best approach is to establish strong roots and healthy growth pattern prior to working a collected tree. From my experience the minimum time is one full year of growth and sometimes up to three years.
Designing a tree to set the bones when one does not even know which branches they will have to work with can be problematic.
I would recommend erring on the side of caution. Wait longer if you are unsure. A stronger tree will respond better to Bonsai Techniques and develop faster in the long run than a weak tree!
Some species respond better to collection and are more likely to be recovered and healthy in a shorter period of time. However individual trees will vary due to their condition when collected and the actual collection process. The best guideline is the observation of healthy new growth and plenty of foliage to work with.