I've grown Toy Choy for several years now. It is a baby bok choy that is harvested at 10 weeks. They prefer cool (almost cold) weather. I start the seeds indoors starting in January and then every few weeks after that. I bought the seed in 2013 and in 2017 I still had a germination rate of 82% with seeds kept either in the refrigerator or in a very cool room.