50-60 days to maturity. Lactuca sativa ‘Okayama Salad’. Okayama Salad Lettuce Seeds. Non-GMO, cool-season annual heirloom. This early-maturing butterhead lettuce is a Japanese variety known for its delicate flavor and resistance to heat. Deep green leaves form small but delightful heads of tender lettuce. Okayama Salad has moderate cold tolerance and moderate resistance to bolting. Lettuce is adaptable to many growing conditions but likes it cool around 60-65F. These lettuce leaves are so tender, buttery, and delicious that you will want to plant them every year! Approx. 28,400 seeds / oz.