This article shows how hypnosis can provide a useful framework for understanding therapeutic horticulture. Within this framework, data from in-depth interviews with 12 volunteers attending Cherry Tree Nursery—a sheltered work project for people with severe mental illness—provided conceptual groupings of reported experiences: rapport, induction, change in conscious state, relaxation, a safe place, therapeutic change via reframing and symbolic thinking, and confidence boosting. Natural environments and nature-based activities are thus contextualized as spaces and situations within which therapeutic change is more likely to occur. The concept of the restorative environment therefore becomes one component of the overall process—inducing a mental and physical state which is open to change, less egoistic, and socially oriented—but not in itself sufficient to bring about the effects described in the literature. Longer-lasting beneficial effects also require appropriate client-centered guidance, wherein the client creates an internalized environment which endures when they return to their everyday life. The described framework unifies previously disparate therapeutic domains and suggests more focus is needed on ‘induction’ processes, activities appropriate to the client’s mental state, and the settings within which any therapeutic process occurs. Furthermore, cases in which people do not benefit from being in natural environments may indicate incongruencies in concurrent guidance or merit the consideration of a new concept of “nature-susceptibility.”