Boxwoods (Buxus) are popular evergreen shrubs often used for formal hedging and landscape structure. Boxwoods are generally drought-tolerant, but only after they have been properly established in the landscape. This tolerance stems from developed root systems, which access deeper soil moisture reserves unavailable to newly planted shrubs. Even established plants may require supplemental water during periods of extreme, prolonged drought.
The Critical Establishment Period
Achieving true drought tolerance depends on the plant’s first 18 months to two years in the ground. During this establishment period, the focus must be on encouraging the root system to grow deep and wide. Shallow, frequent watering is detrimental because it promotes surface-level roots, which dry out quickly when rainfall is scarce.
A deep and infrequent watering strategy is necessary to train the roots to seek moisture deeper in the soil profile. New boxwoods require approximately one inch of water per week, delivered slowly to penetrate the root zone to a depth of 12 to 18 inches.
Proper planting also aids establishment. The top of the root ball should be set slightly above the surrounding soil line to prevent the plant from settling too deeply. Boxwoods need well-drained soil, as excessive moisture can lead to root rot. Once the roots have fully colonized the surrounding native soil, the shrub will be far more equipped to handle extended dry spells.
Recognizing and Addressing Drought Stress
Even a well-established boxwood may exhibit signs of stress during a severe drought. The earliest visual cue is a change in foliage color, which may appear orange, bronze, or have a dull, grayish cast instead of the typical vibrant green. In a drought-stressed plant, the damage often appears uniformly across the entire shrub, distinguishing it from the localized patterns of fungal diseases.
When these signs appear, immediate intervention involves a deep soaking of the root zone. Watering should be done slowly using a soaker hose or drip irrigation to ensure the water penetrates the soil deeply without creating runoff. Applying a two- to three-inch layer of organic mulch around the base helps conserve soil moisture and moderates soil temperature.
Keep the mulch several inches away from the trunk to prevent moisture buildup that could encourage disease. During periods of stress, avoid activities that place additional demands on the plant, such as pruning or applying high-nitrogen fertilizers. Pruning removes photosynthetic material and forces the plant to divert energy to healing and new growth, which is difficult when water reserves are low.
Selecting Drought-Hardy Boxwood Varieties
Not all boxwood cultivars share the same degree of natural toughness, making varietal selection a factor in minimizing future watering needs. Species like Japanese Boxwood (Buxus microphylla var. japonica) and many of its cultivars are known for their tolerance to heat and dry soil conditions.
Specific cultivars noted for their drought performance once established include ‘Green Mountain,’ ‘Chicagoland Green,’ and ‘Baby Gem’. These varieties have been selected and bred for enhanced resilience, making them a better choice for drier climates or areas prone to water restrictions. While all boxwoods benefit from establishment care, selecting a tougher variety reduces the frequency of supplemental watering required for a mature plant. Conversely, some traditional European varieties may require more consistent moisture to maintain their appearance and health.