As arbs go, it IS a dwarf :-) But that only relates to rate of growth and not necessarily ultimate size. However, growing in a container does slow growth and is a naturally dwarfing process as well.

The 'correct' size of the container will depend on the size of the plant. Since this is a globe shaped arborvitae, I'd prefer to see it in a container with a circumference that matches the conifer's spread. Or slightly larger.......but I would not like the appearance of a too large plant in a too small container so that it overhangs the pot.

The bottom branches should not be browning out. I would check that you are using a high quality, fast draining potting medium and that watering is appropriate to both the plant and the media. And that it is not buried too deeply.

But that only relates to rate of growth and not necessarily ultimate size.

==>>> in conifers ... dwarf is descriptive of ANNUAL growth rate ... this one each year.. grows slower than others ... here is a chart that defines such ....

http://conifersociety.org/conifers/conifer-sizes/

also .. in conifers ... many estimates are at ten years ... and you can presume they can be twice as big at 20 years ... etc.. as trees... they never really stop growing.. at some magical height ...

but also.. as trees.. its not really a pot once and forget job... they often need to be repotted ...

also.. media wears out ... which usually means it can become a water management problem ... another reason that they need to be repotted every few years or so ...

without a pic.. its hard to tell you whether to remove brown part right now ... the key is to search growth tips.. and see if there are viable buds... that will sprout this spring.. and regreen those bare branches ...

also.. as trees .. they grow in tree time ... which is slow.. compared to other plants .... i think you are a bit early ... [i dont know where you are] ... to be trimming off parts that appear dead ... why dont you give it a few months.. to see what buds out.. and then do some artistic pruning of for sure dead parts ...

a pic and location might also help us help you figure out why it browned over winter ... weather last summer as well as during winter.. will lead us to some conclusions ...

its easier to cut later.. rather than try to glue parts back on.. because you have spring fever.. and did something too soon ... lets just see what happens ... a month or two isnt going to make a difference...

ken

ps: in a reply.. use the camera/photo icon below the box you type in.. to add pix to a reply ... of this post ...