A mobile web application called PropG was developed for students to quickly access more than 270 glossary terms defined in a plant propagation textbook. The functionality and usefulness of the app was evaluated by 53 students enrolled in a semester-long online course in plant propagation. Means of pre- and post-test responses to 17 knowledge items showed students perceived a significant knowledge gain in the course for each of the subject categories evaluated. Most students agreed or strongly agreed this learning tool was organized and easy to navigate and would use it in the future. Since 2021, PropG received 153,645 total page views, 90,818 unique visits, and 17,216 returning visits, showing its widespread use in plant propagation.