The butterfly bush is readily propagated through stem cuttings of the soft and hardwood portions of the plant. According to Julie Ream of Oregon State University, the butterfly bush is also an invasive plant. The bush quickly spreads through seed dispersal and can overrun other growing areas. Even trimming the butterfly bush, without adequate cleanup of the stems, will result in the cuttings taking root on bare soil if plentiful moisture is present.
Fill the 6-inch-diameter pots with rich, organic potting soil. The potting soil should be free of any weed seeds.
Take stem cuttings from the butterfly bush plant using the pruning shears. The cuttings should range from 6 inches to 8 inches in length, and approximately 1/4 inch to 3/8 inch in diameter.
Dip the cut end of the butterfly bush stem into the rooting hormone. The white powder should cover up to 2 inches in length of the cut end.
Insert up to four cuttings into a single 6-inch pot, 2 inches to 3 inches deep and evenly spaced. Water the cuttings with one quart of clean water. Allow the water to drain from the pot.
Remove the bottom of the 2-liter soda bottle with the scissors. Keep the plastic cap on the top of the soda bottle.
Place the soda bottle over the cuttings like a mini-greenhouse. Set the pot in a window area out of direct sunlight. Direct sunlight may overheat the butterfly bush cuttings.
Check the cutting in approximately three weeks to four weeks for root growth. Carefully remove a cutting from the pot. The roots should be longer than 1 inch. In most cases, the butterfly bush cuttings will be ready to transplant in approximately 10 weeks to 12 weeks after the original cutting took place. You can transfer the individual cuttings to a single pot. Allow the new transplants to grow in the container for up to two growing seasons before transferring to a permanent location.