A school garden intervention – consisting of both garden-related lessons and gardening activities – had a positive effect on children's knowledge of plant science and nutritional science

A longitudinal, randomized controlled trial examined the effects of a school garden intervention on the science knowledge of low-income elementary school children. The intervention consisted of both gardening experiences and related lessons extending over a two-year period. Participants were 25 second, fourth, and fifth grade students in 49 schools located in four different states in the U.S. Schools participating in the study represented rural, suburban, and urban areas. A survey of science knowledge – administered at baseline and at three different times during the intervention – focused on nutritional science and plant science. Results indicated that science knowledge increased from baseline to follow-up more for the intervention group than the control group of children. Science knowledge scores overall, however, were very modest. Robustness of intervention -- based on both garden activities and lessons delivered – was determined for each classroom using a GIF (Garden Intervention Fidelity) scale. One subscale of the GIF focused on the number of garden-related lessons delivered; the other on the number of fruits and vegetables planted, harvested, and distributed. Data was collected by trained Cooperative Extension educators in each of the participating states. Results revealed a dose-response relation with science knowledge – that is, higher scores on the GIF-Sum were associated with significantly higher science knowledge scores. In other words, more substantial intervention implementations corresponded to stronger treatment effects.
This study was designed to address some of the methodological concerns evident in earlier research on the impact of school gardening programs on academic performance. It did this, in part, by employing random assignment to intervention with a large sample of children and by considering the extent to which the “dose” of intervention affects children's science knowledge. In addition to adding support for school gardening as a pedagogical tool, this study also contributes to the literature by associating greater science learning with the robustness of garden interventions.