I also started some celery from seed in peat pellets.
Well 2-3 weeks ago, I planted both out in the garden....after a very gradual hardening off process. Well the celery grown from seed has thrived and looks well.
But the grocery store celery (both stalks) has gone by the wayside.
The decline started almost immediately. I probably should have planted the grocery store celery in soil sooner than I did. Seems as though it didn't handle the transition from water to soil well at all.