60 Days to maturity. Raphanus sativus. Starburst Chinese Radish Hybrid Seeds. Cool Season Annual. Starburst radishes are part of the watermelon radish group, which means that you’ll find bright red flesh under that clean white skin! This variety is best planted in early spring or fall, making it one of your earliest garden treats. The roots will grow as big as tangerines. In some parts of China, watermelon radishes are carved into flower shapes! ~ 3,500 seeds / oz.