BackgroundGardening has been associated with greater fruit and vegetable intake, but few randomized trials have been conducted.ObjectivesWe sought:1) to determine changes in fruits and vegetable intake combined and separately from baseline (spring) to harvest time (fall), as well as from baseline to winter follow-up, and2) to identify the mediators (both quantitatively and qualitatively) between gardening and vegetable intake.MethodsA randomized controlled trial of community gardening was conducted in Denver, Colorado, USA. Post hoc quantitative difference score analysis and mediation analysis were conducted by comparing intervention group participants who were randomized to receive a community garden plot, plants and seeds, and a gardening class with control group participants who were randomized to remain on a waitlist for a community garden plot (n= 243). Qualitative interviews were completed with a subset of participants (n= 34) and analyzed to explore the influences of gardening on diets.ResultsThe average age of participants was 41 y, 82% of them were female, and 34% of them were Hispanic. Compared with control participants, from baseline to harvest, community gardeners significantly increased their intake of total vegetables by 0.63 servings (P= 0.047) and garden vegetables by 0.67 servings (P= 0.02) but not combined fruit/vegetable or fruit intake. There were no differences between the groups from baseline to winter follow-up. Community gardening was positively associated with eating seasonally (P= 0.02), which had a significant indirect effect on the association between community gardening and garden vegetable intake (bootstrap 95% CI: 0.002, 0.284). Reasons qualitative participants gave for eating garden vegetables and making dietary changes included the availability of garden produce; emotional attachment with the plants; feelings of pride, accomplishment, and self-reliance; taste and quality of garden produce; trying new foods; cooking and sharing food; and increased seasonal eating.ConclusionsCommunity gardening increased vegetable intake through increased seasonal eating. Community gardening should be recognized as an important setting for improving diets.This trial was registered inClinicalTrials.govas NCT03089177 (https://clinicaltrials.gov/ct2/show/NCT03089177).