Pruning saltbush in a region to which it is not endemic

I raised this saltbush from seed a few years ago. My climate is not conducive to its growth so I placed it in a pot fashioned from an old pool sand filter.

This year has been extraordinarily dry so you would think that the saltbush would thrive and perhaps even reach the width and height that it does in its natural area. But no, it has been struggling and when it started dying off, my brother who lives in outback South Australia, suggested I give it a hard prune.

Well, here is the new growth!