Take your store bought celery. The one you used all the stalks on & are about to throw away in the trash. (Or in our case, to the animals.) Make a clean cut all the way across the top & a thin slice off the bottom. Put in water & it will start to grow. When I have time, I am going to take this plant & put it in our garden. You plant it will stalk side up, just dig a small whole, fill it with water & set the end in the whole. Cover it with an inch or so of soil & water thoroughly. I plan on getting a whole row growing at different stages so I always have plenty of celery in the garden.
The plant above is about a week old. I am so excited to grow my own celery & to propagate it out of the stuff I bought from the grocery store. I couldn't help, but share. So next time don't throw your celery in the trash, grow your own.