The Japanese Boxwood (Buxus microphylla japonica) is a popular, dense, evergreen shrub valued for its versatility in the landscape. This variety is often chosen for its superior heat tolerance compared to other Boxwood types, making it a robust choice for many climates. Its small, bright green leaves and compact growth habit make it an ideal selection for formal hedges, garden edging, or intricate topiary designs. Successfully establishing this shrub requires careful attention to its specific environmental needs.
Selecting the Ideal Planting Site and Soil
Choosing the correct planting location is important for the long-term health of Japanese Boxwood. This shrub performs best in a location that receives full sun to partial shade, though a sunny position is preferred for the densest growth. Planting should occur during the dormant seasons of fall or early spring, allowing the roots to establish before the stress of summer heat or deep winter cold.
The most important soil requirement is excellent drainage, as Boxwoods are highly susceptible to root rot in waterlogged conditions. While Buxus microphylla japonica tolerates a wide range of soil types, it prefers a pH that is slightly acidic to neutral, specifically between 6.5 and 7.5. Heavy clay soil should be amended generously with organic matter, such as compost or well-rotted manure, to improve aeration and facilitate proper water movement.
Step-by-Step Planting Guide
Preparation begins by digging a hole that is two to three times wider than the root ball but no deeper. This wide hole gives the shallow, fibrous roots easy access to loosened soil, encouraging rapid lateral growth. The depth must ensure that the very top of the root ball sits slightly above the surrounding grade, a technique known as planting high.
Before placing the shrub, examine the root ball carefully. If the roots are densely matted and circling, they must be scored or gently loosened to encourage outward growth. For balled-and-burlapped plants, remove any twine and pull back the burlap from the sides once settled in the hole. If the burlap is synthetic, remove it completely; if natural, cut away the top portion to prevent moisture wicking.
Carefully position the Boxwood in the hole, ensuring it is straight. Use the original excavated soil to fill the hole, breaking up large clods and gently tamping the soil to eliminate large air pockets. Avoid compacting the soil too firmly, which restricts the flow of water and oxygen to the roots. Use the remaining soil to create a low, circular earthen berm just outside the planting area to contain water during establishment.
Post-Planting Care for Establishment
The first few weeks after planting are important for overcoming transplant shock and ensuring root establishment. Immediately after backfilling, provide a deep, thorough watering until the entire root zone is saturated. This initial soaking settles the soil around the roots and eliminates any remaining air pockets.
For the first year, the shrub requires consistent watering, especially during dry spells. Keep the soil evenly moist, but allow the top layer to dry out slightly between waterings to prevent root rot. Deep soaking less frequently is generally better than light, daily sprinkling, and monitoring soil moisture by hand is the most reliable method.
Apply a 2- to 3-inch layer of organic mulch, such as shredded bark, around the base of the plant to regulate soil temperature and conserve moisture. Keep the mulch pulled back several inches from the trunk. Mulch piled against the stem traps moisture, increasing the risk of disease. Avoid applying heavy fertilizers during the initial establishment year, as the plant should focus energy on root growth rather than new foliage.
Ongoing Maintenance and Shaping
Once the Japanese Boxwood is established after the first year, a long-term care plan maintains its health and desired shape. Pruning is best performed in late winter or early spring before new growth emerges, though light shaping can be done throughout the growing season. For formal hedges, light shearing can be done several times during spring and summer to maintain a crisp, dense surface.
Avoid pruning too early in the spring, as this stimulates tender new growth vulnerable to late frosts. If the shrub becomes too dense, selective thinning cuts should be made deeper to increase air circulation and allow sunlight to penetrate the interior foliage. This technique helps prevent the development of dead zones inside the shrub.
Annual fertilization should occur in late fall or early spring, aligning with the Boxwood’s primary root growth periods. A slow-release, balanced granular fertilizer, or one slightly higher in nitrogen, is suitable for promoting healthy green foliage. Avoid fertilizing in late summer or early fall, as this encourages new growth easily damaged by the first winter freeze. Regularly inspect the dense foliage for signs of pests like the Boxwood leafminer or the fungal disease Boxwood Blight to ensure issues are addressed early.