Grow an Avocado tree
Food-That-Magically-Regrows-Itself. Did not work for celery for me. Looked like it would but then it just shot up the middle. Most of the others work or should work though
Cut wine bottles for planting herbs. Plant your favorite herb and fill up the bottom with water. It will sip the water thru the rope.
(spotted by @Ermelindawfl957 )
Awesome DIY Vertical Herb Garden
Use recycled containers by fastening them on a fence or wall for your herbs.
vertical succulent garden how to
Grow Onions from Discarded Onion Bottoms
Learning how to grow your own spices indoors.