These are less tart and less astringent than Nagami but still tart. The Fukushu rind is much thicker so it seems far sweeter overall. Also, the Nagamis often have a slight bitter taste if they aren't 100% orange, which I haven't seen with Fukushu.
The container is probably about four actual gallons, not sure how that translates to nursery pot sizes. I'm using rolls of the rootmaker material so I just construct them to be a little bigger than the rootball.