Sweet potatoes are simple to root with just water and sunlight. First, fill a container for the cutting with water, and allow it to rest overnight. Examine the parent plant for a node, which is a bump in the stem that may have other smaller bumps around it. Take a cutting of the plant from below the small bumps, if they are present, or below the node if they are not. Be careful not to damage the node.
Pinch off any leaves that surround the node. Stick the stem into the container of water, making sure the water covers the node. Partial sun is ideal for rooting the cuttings as too much sun can encourage algae growth in the water. With enough sunlight, roots should appear in four to five weeks. Weekly water changes prevent unwanted algae and rotting.
Once roots are established, remove the cutting, and store it somewhere cool and away from sunlight for up to three days to harden off the roots. This increases the plant’s chances of surviving planting. If planting indoors, use a potting mix with high peat-moss content, or mix one part peat moss with one part houseplant potting mix. If planting outdoors, choose a location with partial shade. To plant the rooted cuttings, gently cover the roots with potting mix or soil.