This dissertation explores the transfer and utilization of European pasture grasses and other fodder crops in New South Wales (Australia) and the Cape Colony (South Africa) in the late-eighteenth and early nineteenth centuries. It examines attempts in the period directly following the loss of the thirteen American colonies to replicate the Enlightenment-era mixed husbandry (based in sown fodder crops) of the British Isles in these fledgling antipodean colonies. It calls into question Alfred Crosby’s model of ecological imperialism (the spread of European biota in temperate colonial possessions) as a phenomenon occurring largely outside of official oversight; it destabilizes an enduring dichotomy in imperial historiography between land and labor intensive agriculture in the Old World and land extensive, destructive agriculture in the New World; and it suggests ways in which to merge scholarship on the ideological and scientific underpinnings of imperialism with the actual “groundwork” of settlement. The dissertation argues that a particular form of agrarian improvement (grass-based mixed husbandry) was the driving force of colonial agricultural development in New South Wales and the Cape in the period between 1780 and 1840, but that this distinctly metropolitan version of improvement came into constant conflict with new environmental, political, economic, and social realities in these fledgling colonies, as well as with competing models of improvement (e.g. commercial pastoralism). Ecological imperialism was highly orchestrated in these two British colonies; however, in the period before the scientific governance of nature at the hands of a powerful colonial state, the combined environmental, political, economic, and social challenges to mixed husbandry meant that ecological imperialism was extremely hard-won—if it was won at all.