This study examines an out-of-school time program targeting elementary-aged youth from populations that are typically underrepresented in science fields (primarily African-American, Hispanic, and/or English Language Learner participants). The program aimed to foster positive attitudes toward science among youth by engaging them in growing plants hydroponically (in water without soil). Participants' attitudes toward science, including anxiety, desire, and self-concept, were examined through pre-post survey data (n = 234) over the course of an afterschool program at three separate sites. Data showed that participants' anxiety decreased and desire increased for both male and female participants over the program. Self-concept increased for female participants at all three sites but did not change significantly for male participants. Participants' first language (English or Spanish) was not a factor in attitude outcomes. The primarily positive outcomes suggest that hydroponics can be a useful educational platform for engaging participants in garden-based programming year round, particularly for settings that do not have the physical space or climate to conduct outdoor gardening. Similarities in positive attitude outcomes at the three sites despite differences in format, implementation, and instructor background experience suggest that the program is resilient to variation in context. Understanding which aspects of the program facilitated positive outcomes in the varied contexts could be useful for the design of future programs.