Nature connectedness counts as a crucial predictor of pro-environmental behavior. For counteracting today's environmental issues a successful re-connection of individuals to nature is necessary. Besides the promotion of knowledge transfer the aim of the educational program presented in this study is to connect students to their environment. This research explores the impact of an outdoor environmental education program on primary and secondary school students' nature connectedness with regard to the extent of their nature experience and participant age. The intervention was implemented in two durations: one-day and five-days. Participants were divided into four subsamples from seven up to 18 years of age. Findings suggest that both intervention types evoke immediate shifts towards a stronger nature connectedness among students (p < 0.001). Notably, the five-day outdoor education interventions were significantly more effective in sustainably promoting nature connectedness compared to one-day field trips (p < 0.001). Seven to nine year old students performed the strongest shifts towards nature. The value of short-term and residential outdoor environmental education interventions is discussed.