Start with fresh, mature green onions and cut off the top green stem portion of the onion to leave only the white stem, bulb, and roots.
Keep soil moist, and put the planter in a sunny location.
Keep the soil moist by providing about 1” of water per week and watering 2 to 3 times per week. And put the planter in a warm, sunny location. Green onions prefer full sun and warm to cool temperatures between 55°F and 65°F.
You can harvest the green stems at 6” to 8” tall. Cut the stem for immediate use. Leave approximately 3” of the stem so the plant will stay healthy and continue to grow.