How to Propagate Hydrangea paniculata 'Shikoku Flash'?
Propagate by softwood cuttings in early summer, or by hardwood cuttings in winter

Hydrangea paniculata 'Shikoku Flash' · Hydrangea paniculata 'Shikoku Flash'
Thrives in humus rich soil, that is consistently moist but not waterlogged. Position in sun or part-day shade; in warmer areas, plants may benefit from shade from hot afternoon sun. Mulch in spring, and provide shelter from cold, drying winds. See shrubby hydrangea cultivation for more detailed advice
Propagate by softwood cuttings in early summer, or by hardwood cuttings in winter