Planting Site & Soil Recommendations
Site Selection
Location is very important when planting boxwood. All too often, design elements are considered before site conditions. This has resulted in many healthy boxwood, planted in a poor site, growing weak or even dying. Each individual site will have its own set of conditions. The following is a list of site conditions to consider.
Soil pH
One of the easiest and most important practices to ensure the health of boxwood is to maintain a proper soil pH. When the soil pH is in the correct range, between 6.5 and 7.2, the nutrients in the soil are readily available to the plant. If the pH is below this recommended range, it is too acidic and requires application of dolomitic lime. This type of lime, with its a low oxide content, can persist in the soil for three to seven years depending on application rates, existing soil pH, and soil type. Because agricultural lime, burned lime, and dehydrated lime buffer the soil pH for generally less than one year, they are not recommended for use on boxwood.
Your County Extension Service is an excellent resource for recommendations for properly adjusting soil pH. The soil can also be tested by using a variety of instruments. The benefit of this approach is the immediate determination of the soil pH.
Exposure
Boxwood perform best if given partial sun during the growing season. However, during winter the site should offer protection from both sun and wind. Plants exposed to continual, direct sun in winter will have reddish-brown or yellow leaves due to the loss of chlorophyll. Windy sites in winter can cause the boxwood to lose water faster than it can be absorbed. This also causes a reddish-brown discoloration of the leaves. Boxwood planted close to the south or west sides of buildings and other structures are most exposed to the negative effects of winter bronzing.
Soil Texture
A loamy soil which has nearly equal portions of sand, silt, and clay is ideal. A sandy soil generally does not have sufficient water-holding capacity. Heavy clay soils often lack good drainage, making them overly moist, reducing the important air in the soil. Conversely, when the clay soil dries, it can become exceptionally hard, inhibiting root growth. To correct heavy clay soil, an effective solution is to top dress with organic matter which, as it decomposes, will create pore space for proper root development. In sites where surface water collects, install a tile drainage system before planting to carry off excessive water.
Root Competition
Competition for water and nutrients from nearby trees, shrubs, turfgrass, and ground covers should be avoided. To best protect the boxwood, the site should be free from roots of other plants. Boxwood roots will reach out as past the drip line; with age, many will go several feet beyond. In temporary solutions, the site conditions can be modified by appropriately increasing water and fertilizer applications to compensate for the loss due to root competition. However, an effective long-term solution involves transplanting the boxwood or the interfering plant.
The majority of boxwood roots are near the soil surface. Because of the extensive lateral root system, boxwood should not be planted too deeply or in locations that restrict the spread of the roots. Root development will be stunted if the shrub grows too near the foundation of a house, sidewalk, or other barrier.
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