The aims of this research were to examine whether horticultural activity is appropriate for personality education to prevent reformatory students from redelinquency, to make use of it for developing educational programs and to take advantage of the research as based information. In order to accomplish the purposes, the researches and surveys were taken in four parts targeting 262 reformatory students from five different Youth Detention Centers out of ten centers in the country: simple mental health diagnostic inventory, general characteristics, preferences of personality programs that are currently underway to juvenile delinquents in juvenile protection education institution, and awareness and preference of the plants and horticultural activities. First of all, as a result of simple mental health diagnostic inventory, ‘depression’ appeared to be the highest while ‘hostility’, ‘somatization’, ‘obsessional thinking’, ‘interpersonal sensitivity’, ‘anxiety’ and ‘psychosis’ emerged in the order. Secondly, as a result of preferences of personality programs, ‘social work’ appeared relatively the highest, while ‘Do-dream program’, ‘art therapy’, ‘career exploration’, and ‘sex education’ showed in the order. Thirdly, 53.3% students responded that personality programs through horticultural activities is desirable and 84% appeared that they prefer it. The most preferred plant species were fruit trees (strawberries, apples), flowers (roses, herbs) and vegetables (Scatter cucumbers, tomatoes). The most interesting garden activities were ‘growing (cultivation)’, ‘decorating (decoration and craft)’ and ‘feeling plants (appreciating).’ Therefore, it is well ascertained that juvenile delinquents in juvenile protection education institution consider introducing horticultural programs into personality education positive. Based on these results, it is identified that more various and specialized horticulture programs to prevent reformatory students from redelinquency should be developed for practical use.