What soil mix for my japanese maples

[leatherback]

Also fitted a new water butt at weekend which filled in one night with a decent downpour.

They last few days we got some good storms across europe right!?
Here so much water that I wonder why I spent 3 hours watering my growing beds, which then pretty much eroded away in the downpours!

 

[Bonsainoob88]

They last few days we got some good storms across europe right!?
Here so much water that I wonder why I spent 3 hours watering my growing beds, which then pretty much eroded away in the downpours!

No thunderstorms in northeast but a few scattered across uk in the warmer parts I believe. But enough to fill my butt

 

[Bonsainoob88]

Well looks like my dangerously late repotted tree pulled through the winter and budding out nicely today

 

[Bonsainoob88]

I really do need to get this in a bigger pot now I've worked a good soil mix out .

How big a pot should I go ?