30 to 40 Days to maturity. Raphanus sativus. Shunkyo Chinese Radish Heirloom Seeds. Cool Season Annual. Shunkyo radishes are a hidden gem that originates from Northern China. These radishes grow to 8 inches long, are slow to bolt, and mature quickly, making them an easy crop to grow! Their dark pink skin conceals soft white flesh that has a delightful crunch. Hot, sweet, and colorful, this variety is a must-try for your garden. Plant them throughout your whole growing season, and harvest their tasty roots all summer. ~ 3,180 seeds / oz.