I have acquired a 30 cm juniper (pre bonsai) i would like to thicken the trunk and have it develop before training it to bonsai.It live in a small black 10cm pot and seems to have akadama and "kiryu"?? soil and perhaps other soil? I live in the UK and its approaching the end of May and i would like it to go in a huge pot to stimulate growth before training. What soil mix should I make? I only have 1.5kg of akadama to my disposal and that will only make up 20% of the pot. I have some general compost which is very fine. Some standard compost which is coarser. Please help?
A photo would help - else I'll assume it's the same as what we see often:
A young, underdeveloped tree that needs lots of growth before it becomes interesting for bonsai.
Such trees should be planted in full soil and let grow for a couple of years, to develop a decent trunk.
Do note junipers belong outside.
But do post a picture for a better assessment.
Do note junipers are amongst the trees most often discussed on this forum, so the information you are looking for can be found bu searching the forum for 'juniper'. Also, there's a species guidelines section that - of course - includes guidelines for junipers.
In any case.. Repotting in a huge pot is less productive than you would think. I would work my way up on pot size slowly. Plants need to have a pot not too big for the size of the foliage & water consumption to avoid the substrate staying too wet for too long. Best would be to just put it in a garden somewhere.
First however, think what you want to achieve with the tree, and put some basic styling in the branches now that they are still very flexible. You can do extreme bends, and let the tree grown out. THat would give you more interesting bracnhes and yin later on.
When growing out, make sure that branches that you grow out as sacrifice branches do not shade out the smaller branches you keen in check to later form the basis of your tree. As you know, a tree will need foliage close to the trunk to become a realistic bonsai. Keeping those branches now, will save you years of working on backbudding later on.