How to Propagate Forrest’s butterfly bush?
Propagate by semi-ripe cuttings in summer, or by hardwood cuttings in autumn

Forrest’s butterfly bush · Buddleja forrestii
Grow in well-drained soil in full sun in a sheltered location out of cold winds. Best in warmer counties or city locations. Can be wall-trained on a warm sunny wall. See buddleja cultivation for more detailed advice
Propagate by semi-ripe cuttings in summer, or by hardwood cuttings in autumn