A Fruitful new area of environmental history research can be undertaken on the relationship between plants and health in colonial societies. By using New Zealand as a case study, I demonstrate the strength of settler beliefs in the connections between existing environments, environmental transformation, and their own health. I attempt to reconnect the historiographies of medical and environmental history by arguing that urban settlements- as much as rural areas – were important sites for debates about environmental change and human health. I adopt a broad perspective in order to sketch out the contours of a new field, demonstrating the complicated connections between health, aesthetic appreciation, medicine and garden history. Furthermore, I argue that many environmental-health ideas associated with miasmic theories became incorporated into the microbial ‘revolution’ taking place from the late nineteenth century. Finally, I note that a close study of settler environmental-health ideas reveals a far more ambiguous- a far more anxious – history of European engagement with temperate colonies than the existing historiography on the topic posits. Rather than wholly confident and arrogant agent of environmental exploitation, it reveals that great anxieties about health existed side-by-side with confidence in the environmentally transformative potential of colonisation.