Cornus controversa should be watered thoroughly in dry spells, especially whilst it is still young and establishing itself (i.e. in the first two to five years in the ground). It’s always best to water less often and heavily, rather than little and often, as you want to encourage the roots to grow deeper into the soil rather than stay at the surface.
To help the soil retain optimum water, mulch around the roots in spring (i.e .now). Do this after a heavy watering to lock in the moisture.
I hope this helps. For more detailed care instructions and prompts for this particular tree make sure you add it to your plants in your garden profile!