I think that it is trying to go to seed, I would cut that off...........the top a couple of inches.........do it say that it is a cool veggie I think that it is bok choy, ph should be 6.-7.5............likes fertilizer and moist mulch. I would trim the tops off and cut it short...and cook it......fertilize, lime & mulch...............I just noticed that it goes by 2 names. It's a spring or fall crop..............Summer weather will make it wilt.