How to Water Himalyan tree hydrangea?
Consistently moist root zone, add extra water during warm dry weather

Himalyan tree hydrangea · Hydrangea aspera subsp. robusta
Also known as: robust hydrangea
Grow in moist but well-drained soil in partial shade or sun if the soil remains reliably moist. See shrubby hydrangea cultivation for more detailed advice
Consistently moist root zone, add extra water during warm dry weather