Parasitic plants contain some of the most bizarre and fascinating organisms in the plant kingdom. Yet they are notable for their absence from botanic gardens’ plant collections and conservation strategies. Besides a handful of species, few are widespread in cultivation; indeed we estimate at least 76 per cent of species are entirely missing from collections today, and most of these have never been grown at all. Here, we place focus on the holoparasites, a group of plants long neglected due to their difficulty in cultivation. We review propagation breakthroughs in temperate and tropical botanic gardens to identify guiding principles for the cultivation of these neglected plants. We document the life cycle of a range of parasitic plants, and assess successful and failed attempts to propagate Rafflesia specifically, which has been the focus of decades of research. By uniting isolated case studies from around the world, we identify future directions for the cultivation and possible ex situ conservation of these botanical enigmas at a time when this is needed urgently. Finally, we recommend a dedicated global community of purpose as an intentional step forward: this could take the form of a Global Consortium for Conservation for parasitic plants, or a Parasitic Plant Specialist Group under the International Union for Conservation of Nature.