Cabbage Seeds - Pak Choi - Shanghai. Heirloom, Non-GMO. Annual. Brassica rapa Chinensis group. 10-15 days microgreens; 20-30 days baby leaf; 45 days full maturity. Cool-warm season. This green stem variety is very popular in South China. It has an attractive hourglass shape with glossy, dark green leaves, and thick petioles that are tender and very delicious. It is high yielding and known for its heat tolerance. ~ 6,000 seeds per oz.