Butterfly bush, also known by its scientific name, Buddleja davidii, is a perennial shrub native to warm areas of North America, Africa, Asia and South America. Gardeners value the plant for its ability to attract beneficial insects to the garden and for its attractive, brightly-colored foliage. Butterfly bush grows quickly and may reach its full mature size in just a few growing seasons. With proper care, the plant may reach heights of up to 10 feet tall and 10 feet wide. Butterfly bush is hardy in zones 5 through 9 and thrives in most areas of the United States.
Plant butterfly bush during early spring so the plant can become established before winter. Choose a planting location that receives full sunlight throughout the day and has fertile, well-drained soil for the best results.
Use a shovel to dig a hole in the soil twice as deep and three times as wide as the root ball of the butterfly bush. Set the root ball into the hole and back-fill with soil. Water thoroughly to collapse air pockets and bring moisture into contact with the roots.
Spread a 3-inch layer of mulch over the soil to insulate the plant's roots and suppress the growth of weeds. Begin the layer of mulch 3 to 4 inches from the crown of the plant, or the area where the stem meets the roots, to allow proper air circulation.
Water deeply once every two weeks during the spring and fall months. Decrease the frequency of watering to once per week during summer. Do not water the plant during winter, when it is not actively growing.
Fertilize butterfly bush twice per year, once in early spring and again in fall. Use a slow-release fertilizer to slowly deposit nutrients into the soil throughout the year. Apply following the manufacturer's directions.
Prune butterfly bush in early spring while the plant is still dormant. Use pruning shears to cut back the previous year's growth to about 12 to 18 inches in length to promote a compact growth habit. Remove any damaged or diseased limbs to increase the health of the plant.