What Are the Sunlight Requirements for saw-toothed hydrangea?
Partial shade

saw-toothed hydrangea · Hydrangea serrata
Grow in moist but well-drained, humus rich soil, in a lightly shaded spot with shelter from cold, drying winds. Mulch annually in spring. Soil additives may be required to maintain specific flower colours. See shrubby hydrangea cultivation for more detailed advice
Partial shade