How do future medicines become cultural heritage and what does it tell about the experimental modes of care in which environmental activism transforms our notions of planetary habitability? Starting from the premise that herbal gardens are important sites where such tinkering has been taking place, this paper explores a recent project of revitalizing medicinal plants in a rural community of Western Japan. The Morino Herbal Garden, a cultural heritage site in the mountainous region of Nara Prefecture, was founded at the beginning of the 18th century from a small set of seeds brought from China. In the span of a couple of decades, the garden evolved into one of the dedicated experimental locations of a nationwide infrastructure aimed at facilitating the domestic production of herbal drugs. Today, this historic garden is not only a cultural heritage site for tourists, but a model for another plot nearby where local citizens grow medicinal plants for their own health and wellbeing. By tracing the seeds of a posthuman politics of resilience in these two herbal gardens, my aim is to suggest an alternative to static notions of global, local, planetary or native dimensions of heritage. Medicinal plants may grow in the wild or are cultivated, but mostly somewhere in between. In herbal gardens, such relational encounters across difference are not only something essential for them to exist, but they are also what make them scalable. Thinking through the question of how do cultural traditions and medicinal plants come to cultivate and be cultivated by one another may help us to highlight the stakes that are involved in such practices of scaling. At these crossroads, as I will argue, medicinal heritage becomes a posthuman experiment of cohabiting the planet and our bodies with other living things.