try eucalyptus neglecta---naturally a rather bushy plant that should tolerate periodic cutting back and one of the most tolerant of southeastern heat and humidity in the summer and periodic winter cold. cinerea ("dollar gum") is often sold as an "herb" plant and though often cut back by cold should have a reasonable chance of returning perennially if placed in a favorable micro-climate (warm south or west exposure protected from cold winds) and mulched around the base. hope this helps.