Background: Growing evidence from environmental psychology, epidemiology, neuroscience, and landscape architecture has highlighted the contribution of urban green spaces to mental health and well-being, leading to a gradual shift in planting design from a purely aesthetic practice toward a health-oriented approach. Despite the expanding literature on nature–health relationships, a comprehensive framework explaining the dimensions of therapeutic planting design and the challenges of this emerging paradigm remains lacking. This study critically examines the theoretical foundations, empirical evidence, and transition challenges of therapeutic planting design and proposes a conceptual framework for evaluating and guiding this shift.

Methods: A critical review was conducted using the SALSA framework (Search, Appraisal, Synthesis, and Analysis). Literature was retrieved from Scopus, PubMed, Google Scholar, and SID. Of the 1,624 records initially identified, 80 studies published between 2015 and 2026 met the inclusion criteria, underwent quality appraisal, and were synthesized using Braun and Clarke’s thematic analysis.

Results: The findings indicate that three major theoretical perspectives—Stress Reduction Theory, Attention Restoration Theory, and the Therapeutic Landscapes approach—constitute the conceptual foundations of health-oriented planting design. Thematic analysis further identified five key challenges: the tension between conventional visual aesthetics and multisensory health-oriented aesthetics, the native–exotic plant dilemma, the misconception of a one-size-fits-all healing garden, the research–practice gap, and the quantity–quality gap in urban green space planning.

Conclusions: The findings demonstrate that urban planting design is undergoing a paradigm shift from a predominantly aesthetic approach toward a health-oriented one. The proposed five-level conceptual framework, the principal contribution of this study, conceptualizes this transition as a continuum from ornamental planting to integrated health-oriented planting design and provides an evidence-informed basis for the design, evaluation, and policy development of urban green spaces.