How to Grow Celery from the Store Cut off all stalks and place heart in water with good sunlight. Change water every few days. Watch new leaves grow! Transfer to soil when 2 tall. Don't harvest until 8 tall.
Celery Harvest: Picking Celery In Your Garden - Learning how to harvest celery is a worthwhile goal if you have been able to grow this somewhat difficult crop to maturity. The time for picking celery and how it's done can be found in this article.
Growing Celery from the stalk - important that this site tells you to put it in dirt after 3 days - and I have to say that would have been a good idea. Mine rotten from leaving it in the shallow dish of water too long :(
It's apparently quite simple: just stand the base in a small dish of water for a week or so until new leaves appear in the center. The leaves will be yellow at first, and once they really emerge and turn green, you can plant the celery in the ground or in a pot.