How to Propagate Hydrangea alternifolia?
Propagate by softwood cuttings in early summer or hardwood cuttings in winter

Hydrangea alternifolia · Hydrangea alternifolia
Grow in any moist but well-drained soil in partial shade or grow in sun if soil remains reliably moist. Improve chalky soils with organic matter to support good growth. See shrubby hydrangea cultivation for further advice
Propagate by softwood cuttings in early summer or hardwood cuttings in winter