Hi Garden Web Members! I've gotten a lot out of the site, prior to joining, from reading Q&A's between others. Thanks a million!

My garden is new - I just moved and populated a virgin rooftop terrace with easily 35 plants, some of which are large-growing shrubs. I'm anticipating healthy growth of what I already have but would like some winter color. Would it be possible to plant witch hazel together with my syringa vulgaris (lilac) in one big pot? Or would they be better off being in separate pots?

Thanks in advance!