As the populations of many countries are aging, institutions providing support for the elderly increasingly often use nature-based interventions (NBIs) as part of their therapeutic activities. This study aimed to show the impact of 8-week active and passive NBI programs on self-esteem, well-being, and relaxation in the elderly. The NBI programs were conducted in two groups of elderly citizens of Poland: independent senior students and seniors requiring 24 h care. The Rosenberg’s Self-Esteem Scale and the World Health Organization Well-Being Index were used to assess self-esteem and well-being before and after the programs. To assess relaxation, pre–post session measurements of pulse rate (PR) and blood oxygen saturation (SpO2) were used. Our study showed an improvement in the self-esteem, well-being, and relaxation of the participants of both active and passive NBI programs. In all study groups, self-esteem and well-being improved after the programs, regardless of the type of intervention, and after each NBI session, the elderly showed a decrease in PR and an increase in SpO2, which indicated a deeper state of relaxation. Our research showed a greater improvement in the tested parameters in the seniors participating in the passive programs in a garden. This confirms a key role of green spaces in residential areas for the elderly and in nursing homes.