Several of the celery plants that I sprouted last spring (by putting the cut off base of a head of celery in water…then planting in dirt at soon as roots formed) stayed green and grew new stems and leaves during this past summer. In August - before I went off to Texas - I discovered a caterpillar on them. It was a black swallowtail caterpillar. It was a great end to the celery experiment. I don’t know where the caterpillar went after it ate most of the celery…but hope it should be becoming a butterfly soon.