Abstract Background A limited amount of research has examined how nature-based palliative rehabilitation can be implemented in nursing homes for people with dementia, even though evidence suggests that these gardens are underused. This paper will present the study protocol of an intervention study co-designed in an interdisciplinary collaboration with a nursing home for people with dementia, to develop a tailored nature-based palliative rehabilitation program to increase qualified use of garden with the purpose of promoting a range of health outcomes. Methods The study is a single-cased quasi-experimental mixed methods study. The intervention will be developed, designed, and implemented in collaboration with the nursing home, using different co-design tools and methods. The effect of the intervention will be evaluated using the The Neuropsychiatric Inventory Nursing Home version in combination with medication use, a survey on staff burnout, and cameras in the garden to register garden use. A process evaluation with single- and focus group interviews consisting of various stakeholders in the study will be used to gain knowledge on the intervention processes and implementation. Discussion The paper presents new approaches in the field of palliative rehabilitation for people with dementia using nursing home gardens, through interdisciplinary collaboration, participatory co-design approach and mixed methods design. Using both effect and process evaluation, the study will provide unique insights in the role and importance of participatory process, interdisciplinary collaboration, and tailoring palliative rehabilitation activities in gardens at nursing homes to local needs and wishes. These results can be used to guide other nursing homes and renewal projects in the future. Trial registration ISRCTN, ISRCTN14095773. Registered 15 July 2022—Retrospectively registered.