Enhancing water use efficiency in urban green spaces is an increasing concern in hyper-arid megacities. Here we aimed to compare the efficacy of species selection vs. soil management as strategies for reducing water demand of ornamental trees in irrigated green spaces of the city of Lima, Peru. We compared the performance of a popular exotic shrub used as a living fence in Lima’s green spaces with an alternative native species when grown in soils with or without biochar at different levels of soil water availability. Plant water stress and mortality were measured over 6-months. The native species outperformed the exotic in terms of resistance to water stress and suffered less mortality at low levels of soil water. The addition of biochar did not significantly enhance the leaf water potential. Its concluded that improved selection of species could significantly augment water use efficiency in urban green spaces in Lima and beyond.