@raynbow- I don't think that any drastic diet like the celery diet is good to consume for a long time. At least you are getting some nutrients when you eat celery, but I certainly wouldn't recommend eating only celery for more than a few days.
If you are going to try eating the celery diet, I think you should consider talking to your doctor about it first. He or she will be able to give you good advice about whether or not you should try this controversial diet. If your doctor says it is o.k. to do, it will be much safer to try it under his or her supervision for the length of time recommended for you.