How to Fertilize hydrangea 'Rosy Morn'?
Hydrangea feed in spring and again early summer

hydrangea 'Rosy Morn' · Hydrangea paniculata 'Rosy Morn'
Grow in moist but well-drained, humus rich soil, in sun or part-day shade. Mulch in spring, and provide shelter from cold, drying winds. See shrubby hydrangea cultivation for more detailed advice
Hydrangea feed in spring and again early summer