How to regrow your groceries...lettuce, celery, onions, bok choy, garlic, ginger, basil, potatoes

Just cut off the bottoms as shown in the picture
and put them into water until they produce roots,
and then plant them in soil.
I've done this to lots of plants.

 

When I start cuttings in water only there comes a point when there are roots and you need to transplant into soil
-- the roots will only develop into water roots if you don't and there's no nutrition in the water for the plants to continue growing.

I have done this with the trimmed tops of beets and they grow greens (small and tender) very nicely. just keep trying - give the most sun you can.