My experience with celery in the “crisper” is that it does not actually stay crisp.  It usually does not take long before I try to pull off a stalk of celery and find it to be rubbery.  A while back, I heard a tip for how to keep it crisp and I finally tried it out.  Wrap the bunch of celery in tin foil.  This works!  My celery stayed crispy for 2 weeks this way.  Definitely try it if you know you will not be using the whole bunch right away.