Cytisus Goldfinch. Broom

Hi all, I recently bought one of the above plants from a GC. It's in a small pot. My intention is to plant it in a large pot as most advice suggests they don't like to be moved so I want to try to get it right from the start. I think it likes ericacous compost which is fine but most say it thrives in poor soil. I have a lovely big bag of ericaceous compost but I'm presuming that isn't going to be of poor quality. Could anyone advise me what to do as apparently these are beautiful when grown properly.
Thanks in advance

 

Well, not something I've had much dealing with but I do think they also like good drainage, and the best way to make a compost less fertile, and improve drainage, is to add some sharp sand or grit.
If its going to be in the container for a number of years I'd use a JI soil based compost, something like No2 with about 25% sharp sand and 25% of the ericaceous compost just to add a bit more moisture holding capability.

I think most brooms are better if given a nice light trim after flowering.

 

Thanks @pete this has been really helpful. I'll give it a go