Boxwoods (Buxus spp.) are popular, hardy landscape shrubs recognized for their dense, evergreen foliage and ability to be shaped into formal designs. These plants do not require extensive or frequent watering, especially once their root systems are fully developed. Boxwoods are highly susceptible to damage from receiving too much water, making disciplined watering practices necessary. Successful care lies in understanding the difference in water needs between newly planted shrubs and established ones.
Water Requirements for New vs. Established Boxwoods
The most significant variable in boxwood watering is the age of the plant. Newly planted boxwoods need consistent moisture to encourage the establishment of a robust root system. During the first year, providing approximately one inch of water per week, through rainfall or supplemental irrigation, is a good guideline, particularly during hot, dry weather.
This deep watering should be done slowly to saturate the root zone, often to a depth of 12 to 18 inches. This encourages roots to grow downward rather than staying near the surface. Before watering again, check the soil to ensure the top layer has dried slightly by inserting a finger or trowel a couple of inches into the soil.
The period of focused, regular irrigation often extends through the first 18 months to two years after planting. Once boxwoods are established, typically after the second year, their water requirements drop dramatically, and they exhibit strong drought tolerance. At this stage, the plants only need supplemental water during extended dry spells or periods of extreme heat.
Deep, infrequent watering remains the preferred method, as it promotes a resilient root structure. If natural rainfall is less than an inch per week during the growing season, a thorough soaking may be necessary.
Adjusting Watering for Seasonal Changes
Watering needs shift throughout the year, requiring adjustments to the irrigation schedule. During the summer months, monitoring is important, especially when temperatures are high or drought is underway, as the shallow root system can dry out quickly. The goal remains to water deeply when the soil is dry, allowing the root zone to access moisture while preventing perpetual saturation.
The fall season requires preparing the shrub for winter. Late-season deep watering, before the ground freezes, is a necessary practice often called “winterizing.” This soaking saturates the soil and helps prevent winter desiccation, which occurs when evergreen leaves lose moisture through transpiration but frozen ground prevents the roots from taking up replacement water.
Boxwoods may occasionally need water during the winter, especially during warm, sunny spells or if exposed to drying winds and lacking snow cover. Since boxwoods are broad-leaved evergreens, they continue to lose water through their foliage throughout the cold months. If the soil remains unfrozen, a light application of water can help prevent the soil from drying out completely.
Recognizing and Preventing Overwatering Damage
Boxwoods are easily damaged by excessive moisture, so recognizing the signs of overwatering is important. Overwatering frequently leads to root rot, caused by a lack of oxygen in saturated soil, which makes the roots dark and mushy. Above ground, symptoms include yellowing leaves, a decline in vigor, and premature defoliation.
These visual cues can be confused with underwatering, which typically presents as brittle, brown leaves. However, the root condition is the definitive difference. The primary measure for prevention is ensuring the shrub is planted in an environment that guarantees excellent soil drainage. Boxwoods cannot tolerate sitting in soggy soil or areas where water pools, such as near downspouts.
Planting the root ball slightly above the existing soil level allows for settling and helps ensure the crown does not sit in standing water. Amending the planting site with organic matter can improve the soil’s structure, allowing excess water to move away from the shallow roots. Proper drainage is the most effective defense against the root diseases that threaten boxwoods.