Hello i have a hibiscus plant in a large pot which has a potential to become a bonsai since its short and trunk is thick. I live in malta in Europe and temperature at the moment is still 19 Celcius (66F) .I wish to repot it to a smaller bonsai pot. When should i do this?

I would ait untill spring is about to break in your place. I guess malta will not get really cold so you can probably do it the whole winter. But still.. Whenever you expect the plant to start the spring push would be the moment.

Thanks so start of Spring i can also cut back the roots am i right?