Based on the reminiscence therapy, the research aimed to develop the horticultural program with life contexts for the elderly in southern Taiwan, and to explore the effect on overall cognitive function of the elderly. The participants were 17 seniors in one community care center. The research adopted quasi-experimental research of one group pre-test and post-test design of time series, and data were collected by questionnaire surveys and semi-structured interviews. The objective of the program was to maintain cognitive function of the elderly. Twelve activities of the program were implemented once a week and 2 hours for each activity. The program included manual activity, group activity, and outdoor planting activity. The program content was based on farming experience of the elderly and integrated with diverse cognitive function trainings. It was found that the program showed immediate effect and two-week delay effect on promoting overall cognitive function of the elderly. Also, the elderly obtained new planting experience and their learning motivation was enhanced. Additionally, because of integrating with life contexts, the program was meaningful and encouraged the elderly to be engaged in the activities and recall the past. In the process, the elderly enjoyed the exchange of horticulture and life experience.