A process evaluation of a randomized-controlled trial of community gardening to improve health behaviors and reduce stress and anxiety.

As part of the Community Activation for Prevention (CAPS) randomized controlled trial (RCT) of community gardening, we conducted a process evaluation to assess the implementation of a community gardening intervention over nine months, as measured by reach, fidelity (delivery, receipt, enactment), and acceptability. Evaluation instruments included repeated semi-structured interviews with study participants, direct observation of community garden sites, and an exit survey of participants. Primary outcomes were diet, physical activity, and anthropometry; secondary outcomes were stress and anxiety. The CAPS trial included 291 participants (19% non-white; 34% Hispanic/Latino; 35% without a college degree; 58% with income < $50,000 per year). Intervention delivery and receipt were high for environmental supports. Garden social events were offered by 73% of gardens, although only 48% of intervention participants reported attending these events. Of the 145 participants assigned to the gardening intervention, 97 (67%) reported gardening the entire season and reported visiting the community garden a median of 90 min per week (range: 0-840). Of the participants who completed the exit survey (48%), 89% were highly satisfied with the overall garden experience. The CAPS trial was favorably received and implemented with high fidelity, supporting the validity of the trial outcomes. These findings suggest that community gardens are a viable health promotion strategy that can be successfully implemented among new gardeners from diverse backgrounds. Strategies that engage new gardeners in the social aspects of the garden environment and connect gardeners with garden "mentors" or "buddies" to ensure new gardeners achieve success in their first years of gardening are recommended.Trial registration: NCT03089177. Registered 24 March 2017, https://clinicaltrials.gov/study/NCT03089177 .