The amount of water a tree needs depends on its age, species, and weather conditions. However, its loosely based around 10 gallons for every inch of its trunks’ diameter.
To calculate tree trunk diameter:
- Measure circumference of tree around 4.5 feet above the ground.
- Divide the circumference by pi (3.1418..)
- Result is known as DBH (Diameter at breast height) which is why it needed to be measured at 4.5 above ground.