Evergreen trees retain their foliage year-round, meaning they are always losing moisture through a process called transpiration. This continuous water loss makes proper hydration a defining factor in their health and survival, particularly when compared to deciduous trees that shed their leaves. A successful watering strategy for evergreens must adapt to the tree’s age, the season, and immediate environmental conditions. The goal is to provide deep, infrequent watering that encourages a robust root system, preventing the desiccation that can occur when water is scarce.
Establishing a Watering Routine for New Evergreens
The first one to three years after planting are essential for a new evergreen, as the tree works to establish a functional root system outside of the original root ball. During the first two weeks, the tree requires frequent attention, often needing water daily or every other day unless there is substantial rainfall. The focus of watering during this phase must be the original root ball, which is the tight mass of soil and roots directly beneath the trunk.
After the initial two weeks, the watering frequency should be gradually reduced to promote deeper root growth into the surrounding soil. For the remainder of the first growing season, watering every two to three days is necessary for the first three months, and then weekly until autumn. Apply a dose of water that corresponds to the tree’s size, typically one to two gallons per inch of the trunk’s diameter at chest height.
The establishment period extends through the first three growing seasons. During the second and third years, the watering frequency can be reduced to once every ten to fourteen days if no rain occurs. The goal remains deep saturation, moistening the soil to a depth of at least 6 to 8 inches to encourage roots to grow downward and outward. Shallow, frequent watering is detrimental because it keeps the roots near the soil surface, making the tree vulnerable to heat and drought stress.
Determining When and How Much to Water Established Trees
For established evergreens, the watering strategy shifts from a fixed schedule to a needs-based approach. Because these trees have extended root systems, the focus is on deep, infrequent irrigation that encourages the root zone to remain consistently moist but never saturated. The most reliable way to determine if an established tree needs water is to check the soil moisture level.
Use the finger test or a soil probe or long screwdriver. Insert the tool 6 to 9 inches into the soil within the drip line, which is the area beneath the outer edge of the tree’s canopy. If the soil at that depth is cool and moist, no supplemental water is needed. If it is dry and crumbly, it is time to water. This practice prevents overwatering that can suffocate roots by displacing the oxygen in the soil.
When watering, the goal is to saturate the soil to a depth of 12 to 18 inches, which encourages deep, drought-resistant root growth. Sprinkling the surface is ineffective because the water evaporates quickly and promotes shallow rooting. Instead, use a soaker hose or a slow-running hose placed within the drip line to allow the water to slowly penetrate the soil without runoff. A general guideline for the volume of water is about 10 gallons per inch of the tree’s trunk diameter, applied over the entire root zone area.
Critical Seasonal Watering Considerations
Seasonal changes require adjustments to the standard watering routine for evergreens. During periods of drought or extreme heat in the summer, the rate of water loss through transpiration increases significantly, necessitating a temporary increase in watering frequency. Signs of water stress, such as dull or drooping needles and a change in color, indicate that the tree is struggling to replace lost moisture.
The deep hydration provided in the late fall before the ground freezes solid is essential. Evergreen foliage continues to transpire moisture throughout the winter, especially on sunny or windy days, even when the roots are encased in frozen soil and cannot absorb water. Inadequate fall watering leaves the tree susceptible to winter desiccation, commonly known as “winter burn,” where the foliage turns brown as it dries out.
During a mild winter, supplemental watering is necessary for all evergreens, particularly those that are newly planted. When temperatures are above 40 degrees Fahrenheit and the ground is not frozen, water can be applied once or twice a month during prolonged dry spells. This winter watering, done during the midday hours, replenishes the moisture in the soil, allowing the roots to access water and mitigate the effects of continuous moisture loss from the needles.