Celery, romaine lettuce, cabbages & bok choy can all be regrown. I use a square vase. After I cut off the eatin’ part of the celery, I put the bottom in the vase, I use the sink sprayer to water the tops until the water is about 2″ deep. I water daily, easy to remember to do this if you park the vase next to the sink. Within three days, this celery started growing in its center. When the green part reaches 8 to 10″ I will plant the bottom into the dirt, leaving only the new growth exposed. It takes about five months to regrow celery. I plan on doing this with all the celery I buy. I will then, in five months time, have grown my own supply of celery. I have a few good windows that I can plant in some pots later on–when winter comes. I have three heads of romaine lettuce, two garlic cloves & two onions regrowing in my garden.
We live on fresh garlic, every single family member loves garlic & onions. I took two cloves of garlic & shoved them into the dirt, along with the bottom of our onions(the bottom of an onion is the hairy, dry roots), both started growing in the dirt. To have the garlic grow cloves, the greens that shoot up, have to be cut back occasionally.
This is a great idea to do with your children. I can buy my own food, but when i grow something, it tastes so much better. I found a great chart created by Cooking Stoned. & Whole Foods. If you can find the chart, it shows a lot of different things that can be regrown.