I tried that trick with a Farmer's Market bought celery recently and had zero luck. Finally bought a four-pack of celery plants and was surprised at how well they grew without a swamp or any special care.

Celery root (celeriac) is altogether different. It is easy to grow but takes a long growing season to size up and is slow to bring up to planting-out stage from seeds. Seedlings are miniscule for a long time--not the sort of things I would try sowing directly.