Warty barberry is an evergreen shrub that sometimes turns partly reddish etc. The basic color is green. Yours may be getting a different light exposure or experiencing some other difference in conditions that is keeping it green only. Plant it out in the garden or give it to somebody and try something else in the pot.

I grew a whole hedge of this for several years; it got too big (4x4 feet even with regular pruning) so I removed the hedge. I think this plant would need a large container to do well for years. It does have a yellow, nicely scented bloom in spring.

Warty barberry is a fairly common commercial landscape plant in Portland and does reliably get a red speckled appearance in fall/winter, but I've never seen a showy one.

If you like a rich orange bloom in spring, consider the newer dwarfing Darwin barberry. It is not so coarsely thorny, and could do well in a pot long term.

What new dwarf Darwin barberry would that be? Are you thinking of its hybrid, B. x stenophylla? Dwarf forms of that are on the market. None of those I have seen here are new introductions.

B. darwinii is hardy to somewhere around 10 degrees F. I had damage on Camano Island this past winter.

It was new to me at the Canby grower's show in May 2008. My memory was that it was labeled as a dwarfing Darwin barberry. It was a dead ringer for the full-size, except for somewhat smaller foliage and the fact it was covered in blooms and well-branched while less than a foot tall.

But it is more likely to have been the 'Corallina Compacta' variety of B. x stenophylla as you mentioned, I just had darwinii on the brain then and now.