60 to 65 days to maturity. Raphanus sativus. Cheong Du Korean Radish Seeds. Hybrid, cool season annual. Cheong Du radishes are a common, popular variety in Korea. Their name means “green head”, which is quite literal: the roots have green shoulders! They are also quite flavorful and have crisp, well-textured flesh. It’s easy to see why they’re popular! They grow to be eight to ten inches long and weigh around two to three pounds. This is a great variety if you want to try growing Korean radishes. Approximately 4,500 seeds / oz.