55 to 60 days to maturity in spring and 35 to 40 days to maturity in fall. Raphanus sativus. Hybrid Sushiro Korean Radish Seeds. Cool season hybrid annual. Not a big fan of bitter, pungent radishes, but still wanting to grow some in your garden? Sushiro radishes are a Korean variety that would be perfect for you! They are mild and pleasant in flavor and still perfectly crisp and bright. This variety is also known as Altari Korean radishes. Pick up some of these open-pollinated hybrid seeds today for a unique radish experience. ~ 7,100 seeds / oz.