60 to 70 Days to maturity. Raphanus sativus. Wakayama White Radish Heirloom Seeds. Cool Season Annual. Wakayama White radishes come from the Wakayama Prefecture in Japan, as the name suggests. They grow fairly large–12 to 14 inches long and 2 inches in diameter with a great, crisp texture! This daikon variety grows consistent white roots that will never fail to impress your gardening friends! Wakayama White radishes should be planted in late summer to early fall for a winter harvest. ~ 3,500 seeds / oz.