Celery
Cut celery stalks from the base as usual, but instead of tossing that base away, place it in a shallow cup of water on a sunny windowsill, leaving the top exposed. In a matter of days, you’ll notice fresh green growth emerging from the center. Change the water every couple of days and watch the plant flourish, even as outer stalks lose their color and fade. Once the new growth has established, transfer the growing celery into the garden or a pot of soil to continue its development.
Green Onions
Use the white root normally discarded to effortlessly provide a steady and renewable source of green onions. Simply place the roots in a glass, leaving the cut end above water. Left on the kitchen windowsill, the green shoots will continue to grow. Change the water occasionally and an endless supply of this cooking staple is always at hand. This same method may be used to keep fresh leeks or fennel always within reach.
Cabbage
Like celery, cabbage (as well as bok choy and romaine lettuce) can be regrown from the root base. Although cabbage can also be started in water, starting out in shallow soil is sometimes more effective. Make sure to keep the soil especially damp for the first week or two to encourage new growth.
Potatoes
A favorite grade-school project, the eyes of potatoes readily sprout new growth (sometimes even in the pantry). Cut potatoes into pieces and nurture the sprouts in water. Once new sprouts are established, plant in damp soil to grow your own potatoes.
Avocados
That golf ball-sized pit is a giant seed ready to grow into your very own avocado tree. Press three toothpicks into the pit along its center and suspend it in a glass with water covering the bottom half. Change the water regularly and after a few weeks stems will form. Growing this tree is a little more challenging than some other kitchen scrap projects, but is worth the effort. Check out this article for more details on growing your own avocado tree.
Garlic
Plant a clove of garlic in a pot of damp soil and place it in a sunny location. As the garlic scapes (stalks) grow, cut them back to divert the plants resources to developing that glorious root. Garlic scapes are a treat in their own right and the peppery stalks can be roasted or used in pesto.
Ginger
Ginger rhizomes (the “root” used for cooking) are easy growers inside the house, but take a little longer. Plant a piece of the rhizome in damp soil and place in a sunny room, but out of direct sunlight. Shoots will become evident fairly soon, but it will take several months before there has been enough growth to harvest. Once the ginger has developed sufficient growth, pull the plant from the soil for use. Don’t forget to cut off a piece to re-plant!