I personally do not like akadama. I live in a region where we can get frost - thaw cycles of a week or so, for several weeks. If this happens I have only brown sludge in my pots at the end of winter.So I went a different route:
www.growingbonsai.net/characteristics-of-good-bonsai-substrate/
Pines and junipers both belong to conifers, I would say.
Repotting in fall is also an option Clicio. In fact I have 2 junipers that I need to do some work on, and I have been considering using the next couple of weeks to do this. Assuming moist fall conditions, trees get a chance to regrow roots and establish themselves before winter. It is a bit of a risk, as you are not certain when winter will hit, and sometimes summer ends with a flashbang of heat and dry winds. Which is why I normally prefer the early spring repotting. Yet, for the anxious, impatient under us, such as me.. Yeah, late summer / early fall repotting of junipers is not unheard of.
I am still not sure I will do it. I have in the past. But now I need to repot a very good tree, into the first bonsai pot requireing substrantial root work. I do not want to loose this tree. And with me handing over tree-care again soon to my wife due to work travels...
