You can grow onions from an onion! Start by cutting off a piece of the onion, leaving at least an inch of stalk and root attached. Place the cut onion in a sunny spot in your garden, ensuring that it has adequate drainage. Make sure to keep the soil around the onion well-watered - you'll know it's time to water when the soil feels dry to the touch. In 8-10 weeks, you should be able to harvest your onions!