Boxwood (Buxus microphylla 'Compacta')

Overview

Buxus microphylla ‘Compacta’, commonly known as Boxwood, is a highly valued slow-growing, densely-branched broadleaf evergreen shrub prized for its neat, compact habit. This cultivar, ‘Compacta’, retains tiny, rounded, leathery leaves that provide excellent year-round formal structure in small garden spaces. Its extremely slow growth rate makes it an excellent low hedge or border plant where minimal pruning might be needed to maintain shape.

This Boxwood thrives across USDA Zones 6 through 9, preferring locations sheltered from harsh winter elements, as exposure can lead to foliage bronzing. While adaptable to various light conditions from full sun to partial shade, its cultural preference leans toward consistently moist, well-drained loamy soils. Gardeners appreciate Buxus microphylla ‘Compacta’ for its reliability as a foundational evergreen, even though its spring flowers are completely inconspicuous.

The diminutive size of Buxus microphylla ‘Compacta’ makes it particularly useful in modern landscaping designs requiring meticulous detail or in specialized applications like bonsai. While maintenance is categorized as medium, careful attention to watering and winter protection ensures the foliage remains dense and robust throughout the year.

Fast Facts

• Plant Family: Buxaceae
• Plant Type: Broadleaf evergreen
• Hardiness Zones: USDA Zones 6-9
• Size at Maturity:
  • Height: 0.5-1 ft
  • Spread: 0.5-1 ft
• Bloom Time: April to May
• Bloom Description: Greenish-white
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

The best time to plant Buxus microphylla ‘Compacta’ is when the ground is not frozen, allowing the shallow roots time to establish before summer stress. These Boxwoods perform best in evenly moist, well-drained loams, which may be a mixture of sand and clay. While full sun is tolerated, siting plants where they receive dappled shade or several hours of morning sun helps prevent leaf scorch and damage from mites, especially in hot summers.

Consistent watering is crucial, as this Boxwood requires medium water inputs. Because Buxus microphylla ‘Compacta’ features shallow roots, avoid cultivating deeply around the base; instead, apply a 1-2 inch layer of organic mulch like compost or bark to conserve moisture and moderate soil temperature. Pruning should be minimal and delayed until after the threat of the last spring frost has passed, preventing damage to tender new growth stimulated by early pruning.

For long-term health, thin out plants annually to improve air circulation and remove any dead or damaged branches. Proper siting is key to winter success; avoid locations exposed to strong winter winds and intense, full-day winter sun, as these conditions rapidly dehydrate the leaves, leading to unattractive bronzing. Plants propagate well via cuttings when propagation conditions are favorable.

Landscape Uses

The diminutive stature of Buxus microphylla ‘Compacta’ lends itself perfectly to architectural edging where a permanent, low boundary is required. Due to its compact and dense nature, this Boxwood excels as an accent plant in small areas, foundation plantings, or within rock gardens where space is extremely limited.

For bonsai enthusiasts, this specific cultivar is highly valued for its naturally small leaf size and dense branching habit, allowing for detailed shaping over many years. When integrating this dense evergreen into formal designs, use it to contrast textures with softer, mounding perennials or to define pathways alongside low-growing groundcovers that share similar morning sun/afternoon shade requirements.

Standout Features

Flower Qualities

• Insignificant

Noteworthy Characteristics

Buxus microphylla, commonly called littleleaf boxwood, is a slow-growing, densely-branched, broadleaf evergreen shrub. The specific cultivar ‘Compacta’ is known for being extremely slow-growing, potentially reaching only 8-10 inches tall in its first 15 years, and is valued as a bonsai plant due to its small, obovate, light green leaves. While leaves generally bronze slightly in colder winters, this characteristic Boxwood usually recovers its green color by mid-spring.

Tolerances

• Rabbit
• Deer

Potential Problems

Boxwood foliage frequently exhibits bronzing, turning an unattractive brownish-yellow, particularly when plants are sited in open areas facing harsh winters, full sun, and winter winds that cause rapid dehydration. While generally tough, these plants show some susceptibility to fungal issues like blights and leaf spot, and root rot is a risk if drainage is poor. Management involves ensuring proper siting away from exposed winter conditions and avoiding overwatering. Monitor for pests such as boxwood leafminer, mites, and the box tree moth, although the boxwood psyllid is rarely a significant issue for this species.

Frequently Asked Questions

What hardiness zones is Boxwood suitable for?

Buxus microphylla ‘Compacta’ is reliably hardy in USDA Zones 6 through 9.

How large does Boxwood grow?

This compact cultivar of Boxwood typically matures very slowly, reaching a height and spread between 0.5 to 1 foot tall and wide.

When does Buxus microphylla ‘Compacta’ bloom?

The insignificant flowers appear relatively early in the season, typically from April to May, and are described as greenish-white.

What sun exposure does Boxwood need?

Buxus microphylla ‘Compacta’ prefers full sun to part shade; however, afternoon shade or dappled light is beneficial to prevent leaf scorch in hot climates.

Conclusion

Buxus microphylla ‘Compacta’ remains an indispensable choice for gardeners seeking permanent structure on a miniature scale, whether utilized for formal edging or artistic bonsai shaping. This reliable Boxwood offers year-round evergreen interest with low overhead, provided care is taken regarding winter wind exposure and soil drainage. Before planting, ensure your location falls within USDA Zones 6-9 and plan your installation outside of the hardest winter freezes for the best establishment results.

Companion Planting

When selecting neighbors for your Buxus microphylla ‘Compacta’, focus on plants that share similar requirements for moisture retention and light levels, while offering textural contrast. Low-growing shade groundcovers, such as Vinca minor or Pachysandra terminalis, pair beautifully with the tight structure of the Boxwood, enhancing borders or woodland edges. Consider plants with fine foliage or brighter colors, like Hellebores, which bloom in late winter or early spring, providing color while the evergreen foliage of the Boxwood remains dense.

Seasonal Care Calendar

Early spring, just before new growth begins, is the ideal time for annual pruning to shape your Boxwood and promote dense re-growth, provided the risk of hard frost has passed. Mid-to-late spring is when you should apply a light layer of organic mulch around the shallow root zone while watering deeply as the weather warms up. During summer heat, monitor moisture closely, as medium water needs must be met consistently to prevent drought stress which exacerbates winter bronzing. In the autumn, ensure the plant is well-hydrated before the ground freezes; this pre-winter soak is critical for preventing dehydration losses caused by drying winter winds acting on its leaves.