Arborvitae requires careful attention to hydration to thrive. These evergreens are not drought-tolerant and possess a shallow, fibrous root system that makes them particularly sensitive to both insufficient and excessive moisture. Establishing a precise watering routine is the most important factor for their survival, especially in the first two to three years after planting. This routine must be dynamic, adjusting for the tree’s age, local climate, and specific soil conditions.
Watering Newly Planted Arborvitae
The first growing season is a period of establishment where the root system must extend beyond the original root ball. Immediately after planting, the initial watering should be a deep, thorough soaking to settle the soil and eliminate air pockets.
For the first week or two, new plantings may require daily deep watering, especially in warm weather, to keep the root ball consistently moist. Afterward, the frequency should transition to two or three times per week for the remainder of the first growing season, depending on the weather and soil type. The goal is to saturate the area to a depth of six to eight inches, covering the primary root zone.
Apply water slowly and deeply using a soaker hose or by letting a standard hose trickle gently. This technique prevents runoff and ensures the water penetrates the heavy root ball, encouraging roots to grow outward and downward. Before watering again, verify the moisture level by digging down a few inches near the root ball; if the soil feels dry, reapply water.
Watering Established Arborvitae
Arborvitae are considered established after two to three full growing seasons. At this stage, the focus shifts from frequent, localized watering to less frequent, deep supplemental irrigation. Established trees still benefit from consistent moisture, especially during dry spells.
During periods of drought or high summer heat, established arborvitae should receive a deep watering once every one to three weeks. The water needs to penetrate 10 to 12 inches to encourage a robust, deeper root structure. This deep soaking helps the tree draw upon moisture reserves in the subsoil, increasing its tolerance for dry conditions.
Monitoring rainfall is important; supplemental water is unnecessary if the tree receives about one inch of rain per week. If the tree is in sandy soil or is a large specimen, weekly watering may be necessary during extreme summer conditions. The deep and slow application method remains preferred to maximize water absorption and prevent surface runoff.
Recognizing Signs of Water Stress
Arborvitae are susceptible to both overwatering and underwatering, requiring proper diagnosis based on checking soil moisture. Underwatering, or drought stress, typically manifests as the browning and crisping of the foliage, often starting at the tips or on the interior. The canopy may also take on a dull, grayish-brown appearance, and branches may droop.
Overwatering is often more dangerous because it can lead to root rot, which is difficult to reverse. Symptoms include the yellowing of interior foliage or the base of the plant, even when the soil feels wet. This occurs because waterlogged soil starves the roots of oxygen, preventing them from absorbing nutrients and water.
A simple diagnostic tool is the “finger test” or using a moisture meter to assess the soil’s condition six to eight inches beneath the surface. If the soil is muddy or saturated days after watering, overwatering is the likely problem. Dry, crumbly soil indicates a need for more hydration. A tree with root rot may wilt even in wet soil because the damaged roots cannot transport water effectively.
Seasonal Adjustments and Watering Techniques
The watering schedule must be flexible and responsive to seasonal changes. During extreme summer heat, especially when temperatures exceed 70°F, both new and established trees require more frequent watering to compensate for increased evaporation. As temperatures cool in the fall, watering frequency should be gradually reduced to prepare the tree for winter.
Winter Watering
Winter watering is necessary for evergreens, which continue to lose moisture through their foliage even when dormant. If the fall has been dry, a deep soaking just before the ground freezes is important to hydrate the roots. Throughout the winter, on warm days when the temperature is above freezing and the ground is not frozen, a monthly watering can prevent desiccation and “winter burn.”
Water Delivery Techniques
Effective water delivery promotes slow, deep saturation of the root zone. Drip irrigation systems and soaker hoses are recommended because they deliver water directly to the base of the plant, minimizing waste from runoff or evaporation. Applying a three-inch layer of organic mulch around the tree helps conserve soil moisture and regulate soil temperature. Ensure the mulch is kept a few inches away from the trunk.