ABSTRACT: BACKGROUND:Garden-based interventions have the potential to impact young children's health in a number of ways, including enhancing dietary intake, increasing outdoor physical activity, diversifying the gut microbiome, and promoting general wellbeing. A number of recent systematic reviews have either included or focused on garden-based interventions for young children. However, most prior reviews including young children only focus on one health outcome or one setting, making a full summary of prior research assessing the impact of garden-based interventions nonexistent. As such, this umbrella systematic review aims to synthesize the literature on health outcomes of garden-based interventions for young children. METHODS:This protocol outlines the systematic steps we will take to conduct an umbrella review on health-related outcomes of garden-based interventions in children younger than 6?years of age. We will systematically search PubMed, PsycINFO, ERIC, CINAHL, Embase, Scopus, OVID-Agricola, and CAB Direct, including all systematic reviews and meta-analyses fitting the pre-determined inclusion/exclusion criteria. We will double screen at each phase of the review: title/abstract, full text, data extraction, and quality appraisal. We will assess the quality of included reviews using A Measurement Tool to Assess Systematic Reviews (AMSTAR 2). Based on the potential for stark variability in what how reviews report child health outcomes, we will analyze the reviews both narratively and quantitatively, reporting summary of findings tables and iteratively mapping the results. This protocol aligns with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols statement (PRISMA-P). DISCUSSION:This umbrella review aims to summarize the role that garden-based interventions play in health promotion for young children. We will focus on a number of diverse child health outcomes in an effort to comprehensively synthesize the evidence to inform future garden-based interventions, research, and policy. SYSTEMATIC REVIEW REGISTRATION:PROSPERO CRD42019106848.