Hydrangeas like evenly moist soil but not wet soil. It is best to water deeply but only when necessary than wait a couple of weeks and check the soil. If you even think it felt moist, don’t water it and check again in a few days. They need less water than most folks think…nothing kills a plant quicker than over watering. Water by soaking the soil but keep the leaves dry. NEVER SPRAY WATER. Spraying you hydrangea or any of your landscape plants shocks them with cold water and promotes fungal diseases. It would be a good idea to feed your hydrangea and all your other Shrubs, trees and perennials right away. More on that here.