hops don't need lots of water until it's really hot out, and the plant has a lot of leaves to lose water through. this early in the growing season, they don't need that much water since they're living off the energy (sugars) they have stored in their roots. if anything, a lot of hop grower are currently over-watering their hops. just keep the ground moist. make sure that the soil is draining well between waterings. the root need oxygen down there, which isn't happening when they are drowning in standing water.