Further, you can cut back on its fruit output (and subsequent mess) by pruning the tree after flowering. Beyond ensuring you provide 'Atropurpurea' with properly draining soil, this tree does not mind various soil types. The purpleleaf plum tree is hardy from zones 5 to 8, with some potential to be hardy to zone 4. Something to be aware of with purpleleaf plum trees is that they may easily be infected by several diseases or insects, including aphids, borers, and leaf spots. Thankfully, there are also a plethora of companion plants you can grow to encourage a healthier plum tree, including borage (or starflower) and chamomile.