Butterfly bushes are strong plants and have few soil requirements. A position in full sun will encourage vigorous flowering. The Butterfly bush does not like wet feet, a physical soil is not well suited.
In spring, you can propagate the plant by putting the tips of cut branches (about 20 cm) into the earth. The same year the stem branches with flowers will develop. The plant may also be pruned during this period. Without rejuvenating pruning, the shrub will quickly become woody and bloom little.
General care tips can be found here