With most of these vegies you can regrow them from the root if you are after the leaves, however with the exception of carrots, onions, beets (and other root crops) you aren't going to have a root to replant. So you are largely out of luck with what you'll find in the supermarket.

But with a few vegie seeds, you can start all of these plants on your own, and get a continuous harvest of the leaves. That might be a better way to go (and I suspect it will be as fast if not faster than starting from a piece of root on many of them).

I would agree to getting seeds. They're very cheap (cheaper than a single serving of the finished veggie at the store) and you'll get enough seed for usually dozens of plants. You'll also get much better varieties than what you'll find in the store as well.

Collard, Kale, Bok Choi, Spinach, Broccoli can be harvested as green leaves, and will regrow. One of my collard has regrown from its roots, but it took a long while since I cut it flush to the ground.

I plant a green vegetable called Molokai. Some people call it Jewish spinach or Egyptian Spanish. I harvest the green leaves for Cooking or juicing. That puppy re-grows the leaves faster than I can harvest them.
Abe

I just tried planting some celery I bought from the store. I hear you can root it, so giving it a try.

That's why I posted this thread, to find out what vegetables will regrow roots after you buy from farmer's market/grocery store. So far the beets, celery, carrots and bok choy have started growing new leaves after I left in water for a week and then planted in containers. Weird they are growing new leaves without even having roots. I am wondering how long before they will grow roots? Since I planted them in soil I don't want to disturb them if they do develop roots.

Its not a veggie, but you can root a pineapple from the leaves/stem very easily.

Just twist the leaves off the pineapple, then pull about the bottom inch or so of leaves off it to expose the stem. Odds are you'll already see roots under the leaves. Just stick it in moist soil and let it go.

Takes 2 seasons for it to produce a new pineapple though.

Well I was repotting the beet tops which was a few months after I planted them and so far no roots but the leaves are growing but are smaller and smaller and I am wondering if it is finally dying and will not grow roots?

I used to use a juiced but it waste so much.. Not only th fiber but some nutrition.. The best juiced on the market is the Norwalk.. But it cost thousands of dollars.. I was thinking about making one.. I bought a vitamix and that puppy blends up anything in juice! Can't live without it! If you are going for health beets in particular will kick your but good! Also try ad forage for dandelion,plantain, and stinging nettle.. Try will donsone amazing things to clean you out.. If your interested in juice "vegetable juices by norman walker" is a great one.. If you are really interested in health get the book "detox miracle sourcebook by Robert morse".. The latter is my health bible.. Dr robert morse cured hundreds if thousands if people from everything from leukemia to MS to spinal cord injuries.. He has a free YouTube channel "robertmorsend".. Check him out.. Oh and i agree, just buy seeds they are cheap.. You could always let your plants go to seed and save the seeds..

Good luck,
Joe

I had better luck getting celery to root when I put in water for awhile first, then transplant to soil.