The trick with watering blueberry plants is keeping the roots moist. You don’t want to drown the plants, but it is best not to let them get dry. Once the peat moss gets dry it is difficult to get it moist again when it is in a container.
It is best to water blueberry bushes through a drip system, however overhead watering can be an option for garden centers and nurseries. We have found it most efficient to use overhead watering for 1 gallon containers, and a drip system for our 2 gallons, 3 gallons, and 15 gallon containers. If a overhead system is used it would be wise to have a shade cloth covering the plants so that the tips do not burn. We use a 50% shade cloth. We have found that overhead watering will cause more fungus issues. It is especially important to water the overhead early in the morning or late in the evening to prevent fungus and burning of the leaves. The drip system can be used any time of day, however it is best to use it in the morning, evening, or night.