Rob_phillips wrote:

Apart from in the summer i bury the pot in a large container full of damp substrate to help keep them cool

Rob do you have any pictures of this setup?

Sorry i dont have a pic from previous years and its still to cold and i have no need to set it up yet this year but you can visualize this i use a large rectangle pot about 10 cm deep i block the dranage holes and i bury my small trees in there pots up to the lips or top edge of the pots.
In what ever i have lying around last year it was a mixture of sand and top soil with some gravel in it and i keep it damp all the time and still water my trees aswell. It jist keeps them cool and helps stop them drying out.

Rob_phillips
Do you have many of those? and after they survive, a long hot summer, how do you winter them?

Hi i have 4 mame, and as for over wintering them there all deciduous so dont need too much light so they get wintered in my greenhouse of which i have a fleece coverd 5 teir tempary greenhouse from b and q, inside it and i just take the plastic cover off that and put a fleece version over it.
If its a really cold spell i will move them to the shed next door.
So i avoid freezing at all costs.

I also have a few small shohin trees that i treat the same.