A horticultural activity is a proper theme for children, since it can develop five senses of the children with a hands-on experience. Current study was conducted to investigate whether the horticultural activity could improve the English learning interest and confidence by using related English expressions in English class through the horticultural activity. Student subjects were from two classes (19 students per class) of the 6th grade in an elementary school located in G city, Gyeonggi-do, Korea. Students in the control class took conventional textbook classes and students in the experimental class took English classes through horticultural activities once a week for 12 times. Students in the English class with horticultural activities had higher scores both on interest and confidence than the students in the conventional English class. In case of academic achievement, there was no significant difference in average scores between the two groups. As results of comparing the two groups 30 days after the end of the experiment, the students in the English class with horticultural activities had significantly higher English learning interest than the students in control class, which suggests maintaining the more learning interest after the class with the horticultural activities. There were positive correlation between English learning interest and confidence(r = 0.037, p = 0.039), and also between the English learning confidence and academic achievement (r = 0.586, p < 0.001). Depending on the results, this study could suppose that English learning interest and confidence could be improved in learning processes through the horticultural activities, further possibly improving the academic achievement. Therefore, in order to provide the more effective and significant educational environment to elementary students who have classes with difficult foreign languages, this study suggests that the horticultural activities could be developed for English education of elementary school and they would be effective in educational fields.