It is only my experience. Every year I tried some seed from China or Chinatown. They were planted side by side with seed I got from Wal-Mart. They either grow every slow or don’t grow at all. Some did grow but insect like them. It looks like the seed I got wal-mart has some insect resistant in it. The plant from china may not resist the kinds of insects here or they are commercial variety which requires using pesticides. The weather here also different, day time is hot buy night is cold. The variety grows in southern China may not fit here. The growing season also short, something needs 5 months to grow wouldn’t work out here. I tried some “ Qin Chai”, same result as you, insect eat them. I hate to use pesticide on what I would eat, so have to abandon them. Next time I would try some seeds from Wal-mart. Wal-mart seeds may be tested growing here before are put on shelf. Only variety works are put on market.