If it's in a container, plain bonsai soil. Don't skimp on soil Get a decent prepared mix.So when I repot next year , what soil mixture should I put in .
Next spring before bud break (just as buds about to burst open--this can happen quickly and before the danger of frost and freeze has past--so you will have to have a place that is protected from those until it gets warmer), bareroot the tree, remove all the old soil--hose washing works well. Work bonsai soil well into the roots as you repot. The tree can take it.