Take 4- or 5-inch stem cuttings from a healthy plant. Cut just above or below a node, which is where a leaf is attached to the plant's stem.
Remove the two lower sets of leaves from each stem cutting, along with any flowers or buds that are forming. This will encourage the cutting to grow strong roots rather than flowers.
Place the sprigs in a glass with several inches of water. Check that at least one leaf node is in the water. This is where roots will grow.
Place the glass where it will receive filtered sunlight or bright indoor light.
Check the water level daily, and replenish it as it evaporates.
Watch for roots to appear. In about one week, small white roots will begin to appear at the nodes and bottom of the stem.
Allow the roots to grow a few inches in length before potting.