Choose a healthy onion with a firm base and visible roots
Cut off the bottom 1 to 2 inches of the onion, keeping the root plate intact
Place the root end in a shallow dish of water or moist soil
Keep the base in a warm, sunny location
Change the water regularly if using water
Wait for green shoots to appear
Transplant the rooted base into soil when roots and shoots are well developed
Plant in loose, well-draining soil with the root end down
Space each plant several inches apart
Water consistently to keep soil evenly moist
Harvest green tops as they grow
Allow bulbs to mature fully if growing for onion bulbs