Scallions - In as little as 5 days you can completely regrow a full scallion (or green onion) from the scraps. Leave about an inch attached to the roots and place them in a small glass with a little water. In a few days, you’ll have all new scallions.
How To: 10 Vegetables & Herbs You Can Eat Once & Regrow Forever
10 Vegetables & Herbs You Can Eat Once and Regrow Forever « Food Hacks | "In as little as 5 days you can completely regrow a full scallion (or green onion) from the scraps. Leave about an inch attached to the roots and place them in a small glass with a little water. In a few days, you'll have all new scallions."
Regrow Mushrooms - Plant mushroom stalks in soil with some compost or used coffee grounds and keep them in a moist environment, preferably where it will be cool at night. They can be tricky to grow, and within a few days the stems will either start to sprout new heads or rot.
Basil - Put a few basil clippings with 4-inch stems in a glass of water and place it in a spot with direct sunlight. When the roots are about 2 inches long, you can plant them in pots to grow a full basil plant.
Regrow Cilantro - Like basil, cilantro can grow roots if the stems are placed in a glass of water. Once the roots are long enough, just plant them in a pot. In a few weeks new sprigs will be starting, and in a few months you’ll have a full plant.
Romaine Lettuce - If you have a stem from a head of romaine lettuce that’s still intact, place the stump in a bowl with about ½ inch of water and put it on a windowsill. You’ll start to see new leaves in about 2 weeks, and they’ll be full grown in 3 to 4.
Regrow Ginger - Like onions, ginger root can be planted in soil to regrow, but the process is a lot more lengthy. It can take a few months for it to sprout, and you should be able to harvest a fully grown bulb in 8 to 10 months.
Carrot Greens - The ends of carrots you usually chop off and throw away will grow carrot greens if you put them in a dish with a little water. Set the dish in a well-lit windowsill and you’ll have carrot tops to use as a garnish or in salads.