Water requirements – Seasons
Q: Is the water requirement for trees the same in winter as in summer: two gallons per inch of diameter per day?
A: No. Deciduous trees need no added water in winter, because they have no leaves. Established evergreen trees, though they are stressed by drought, can get by on winter rainfall. The only trees that need water now are newly planted evergreens like magnolia or hemlock. But even then, five gallons every couple of weeks is sufficient.