Water culture method of onion

To hydroponic onion, we must first prepare a big, healthy and full onion ball, peel off its rotten skin and cut off its roots that are not growing well or are too messy. Prepare a transparent hydroponic container, fill the onion with clear water and put it on it. It is best to let its roots just touch the water. Change the water every day at first, every other day after the small roots grow, and every 3-4 days after the green shoots grow on the top.