Any water shortage in the tree will usually be removed overnight. These application hours also minimize pest problems on ground covers and turf. Trees use water night and day, season to season, whether leaves are present or not. Trees use water all year. Dormant season water during winter droughts can help your trees.
Fine soils require careful attention to prevent over-watering and root death.
How Often Trees should be watered once or twice a week in the growing season if there is no rainfall. A few heavy waterings are much better than many light, shallow waterings. A greater proportion of the applied water is utilized by the trees with heavy watering. Also, light watering encourages shallow roots that can lead to more severe drought damage. Once you begin watering you should continued to water until the rains come.