Previous research has shown horticultural therapy (HT) provides both physical and mental benefits to those engaged in the gardening activities. Individuals' willingness-to-pay (WTP) for these benefits, however, is unknown because of the lack of well-defined markets for HT. As such, this study estimates individuals' mean WTP for a HT site in Busan, South Korea. Mean WTP is ≈$170/month U.S. per individual. WTP, however, shows a wide dispersion; the standard deviation of the estimated WTP is ≈$60 U.S. This study provides additional information to the policymakers of Busan concerning the issue of developing a horticultural site for its citizens. This information must be weighed against the costs of developing the site.