Spring Onion
Green onion is perfect for the balcony as it grows upward and takes up very little space. It can be grown in thin containers or even old bottles. It can be grown easily with some sunlight and regular water. Also harvest it from time to time and give new leaves a chance to grow.
Read more: Herbs That Grow in Water: Plant these 7 herbs in glass, the kitchen will remain fresh and health will get tremendous benefits.