Arborvitae (Thuja genus) are popular evergreen trees and shrubs often planted for privacy screens. Due to their relatively shallow root systems, they are highly dependent on consistent moisture during the establishment phase and are susceptible to transplant shock. Ensuring the plant receives the correct amount of water immediately after planting is vital for its long-term survival. A measured watering routine allows the newly planted arborvitae to extend its roots into the surrounding soil without suffering from dehydration or root rot.
The Critical First Month Watering Schedule
The initial weeks require a high-frequency watering regimen as the tree transitions from the nursery container to its new location. During the first seven days after planting, water the root ball daily to keep the soil consistently moist while the roots settle. This daily application helps eliminate air pockets and prevents fine feeder roots from drying out before connecting with the native soil.
For the second and third weeks, reduce the frequency to a deep watering every other day. The goal remains consistent moisture, not saturation, allowing the soil to dry slightly between watering sessions. This slight reduction encourages the roots to start seeking water deeper in the soil column.
As the arborvitae enters its fourth week, the frequency should drop to approximately three times per week, spacing the waterings out further. This gradual reduction pushes the plant to develop a more robust root system capable of supporting its foliage. Monitor the plant closely during this first month, as extreme heat or wind will necessitate a boost in frequency.
Proper Watering Technique
The method of water application is just as important as the frequency during establishment. Apply water slowly and directly to the root ball and the soil surrounding the planting hole, avoiding the foliage entirely. Overhead watering can encourage fungal diseases and is inefficient for delivering moisture to the roots.
Using a soaker hose or a drip irrigation system set to a slow trickle ensures deep saturation. Water should penetrate the soil 8 to 12 inches deep to encourage deep root growth. Shallow, frequent sprinkling promotes shallow roots, making the arborvitae vulnerable to drought stress. Apply approximately one to two gallons of water per foot of the tree’s height during each deep watering session.
Adjusting Frequency for Weather and Soil Type
The prescribed schedule must be adapted based on local conditions, including weather and soil composition. Soil type significantly influences moisture retention. Sandy soil drains quickly and holds less water, meaning arborvitae planted in this medium may need watering at the higher end of the suggested frequency.
Conversely, heavy clay soil retains water for long periods, which can lead to overwatering and root suffocation. In clay-heavy sites, water less frequently but ensure the application is deep enough to reach the lower roots. During periods of extreme heat or drought (above 80°F), increase frequency by one or two sessions per week to compensate for evaporation and plant transpiration. If a week includes significant rainfall, skip a scheduled watering session entirely, provided the soil is already moist.
Ongoing Care After the First Season
Once the first full growing season is complete, the arborvitae is considered established, and its watering needs change. The focus shifts from high-frequency establishment care to deep, supplemental maintenance. The root system is now developed enough to access moisture from a greater volume of soil.
Reduce the watering frequency to a deep soak once every week to two weeks, depending on the climate and rainfall. Established arborvitae benefit from thorough watering during periods of extended summer drought. In colder regions, winter watering is sometimes necessary. If the ground is not frozen and there has been no rain or snow for several weeks, provide a deep watering when temperatures are above freezing to prevent winter desiccation.
Recognizing Signs of Water Distress
Arborvitae display visual cues when receiving too much or too little water, though the symptoms can appear similar.
Underwatering
Underwatering typically presents as browning foliage, often starting from the tips and progressing inward, or a general crispiness to the needles. The soil will feel dry and hard a few inches below the surface.
Overwatering
Overwatering is a common cause of failure in new plantings and can mimic drought stress. Saturated roots are unable to absorb oxygen, causing the foliage to turn yellow or wilt even though the soil is wet. The presence of mold or algae on the soil surface, or a persistently soggy texture, indicates that the roots are suffocating and are at risk of developing root rot.