The butterfly bush (Buddleja davidii or Buddleaia davidii), is known for attracting a large number of butterflies to its sweet-smelling flowers that blossom each year from May until the first fall frost occurs. A butterfly bush adds color and height to any landscape or garden. Butterfly bushes mature best in U.S. Department of Agriculture cold hardiness regions 5 to 10, and grow quickly into large weeping bushes each year. You can root butterfly bush cuttings to grow additional plants in other areas of your yard.
Take butterfly bush cuttings in the morning during the summer months, and from a healthy branch of the bush. Cut off several sections from the branches ranging from 4 to 6 inches long.
Cut off any leaves on the bottom third of the butterfly bush cuttings, advises North Carolina State University Extension. Any large leaves remaining on the cutting can be cut in half to ease water loss and reduce the overall size.
Fill a pot with draining holes with good quality potting soil or a premixed growing medium. NCSU Extension suggests one-part peat and one-part perlite, or one-part peat and one-part sand. Dampen the growing medium with water, and create holes 2 to 3 inches deep using a pencil (or stick) for each butterfly cutting. Holes can be close together, as long as the cuttings (or leaves) do not touch each other.
Pour some of the rooting hormone into a small cup. Dip the bottom of each butterfly cutting into the hormone. Shake the cutting to remove extra hormone material. Carefully put a cutting into a hole without removing the hormone, and firm the soil to support the cutting.
Cover the pot with a plastic bag or plastic wrap to hold in humidity. Place the pot with the butterfly bush cuttings in a site providing indirect sunlight.
Check the cuttings daily. Get rid of any fallen leaves, and mist with water until roots emerge. Pull gently on the cuttings after a week or two, testing for resistance-a sign of root growth. Remove the plastic over several days, and keep watering as needed to maintain moist soil.
Continue growing butterfly bush cuttings “as is” until the following spring, and then transplant to a flowerbed or larger pots. Or transplant each cutting into a 4-inch pot filled with high quality potting soil, when the cuttings root system includes at least two or three, ½-inch long roots, according to the Washington State University Extension.