I am in zone 9b and basil is ready to harvest. I have it in a grow tower now, but seems to be turning light green and loosing its nutrients. Do i pull the whole plant out including roots or clip all the way back? I couldn’t figure out how to load a photo, but one of them is fairly large with big stalks. (2 ft high). If anyone also has suggestions on preserving fresh and dried that would be great also.