50 days to Maturity, 30-35 days as baby Pak Choy. Brassica pekinensis. QD-2 Express Pak Choi Seeds. Annual, Hybrid. Open Pollinated. This tender and sweet variety of pak choi can be planted in the late spring, summer, or fall. It is cold and heat tolerant, as well as slow to bolt. This variety has light green leaves with a yellowish interior and pure white petioles. It is great for salads and stir fry. ~ 10,000 seeds per oz.