Chinese arborvitae (Platycladus orientalis 'Westmont')

Overview

Platycladus orientalis ‘Westmont’, commonly known as Chinese arborvitae, offers gardeners a highly desirable, compact evergreen form perfect for smaller spaces where traditional arborvitae would overwhelm the landscape. This cultivar maintains an upright-globular shape, providing year-round structure and architectural interest. Its slow growth rate makes it exceptionally valuable for low-maintenance foundation plantings or borders.

The foliage of Platycladus orientalis ‘Westmont’ is particularly ornamental, featuring scale-like leaves that emerge dark green and often sport bright yellow tips, sometimes bronzing slightly during winter months. As a member of the Cupressaceae family, this conifer adds fine texture to garden designs that rely on evergreen structure through all four seasons.

Valued for its manageable size—reaching only 2 to 4 feet tall and wide over many years—the Chinese arborvitae is an excellent substitute where space dictates restraint. Its reliability in USDA Zones 6 through 9 ensures widespread usability across many temperate climates, making Platycladus orientalis ‘Westmont’ a versatile choice for structure and color.

Fast Facts

• Plant Family: Cupressaceae
• Plant Type: Needled evergreen
• Hardiness Zones: USDA Zones 6-9
• Size at Maturity:
  • Height: 2-4 ft
  • Spread: 2-4 ft
• Bloom Time: Non-flowering
• Bloom Description: Non-flowering
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

For optimal health, plant Platycladus orientalis ‘Westmont’ in fertile, medium-moisture, well-drained soils. While this Chinese arborvitae thrives best in full sun, it will tolerate some light afternoon shade, though too much shade may cause the compact shape to become less dense. Good air circulation is always appreciated by conifers to prevent moisture issues.

Watering should be consistent during hot and dry periods; maintain medium soil moisture levels throughout the growing season irrespective of rainfall. If you garden in colder areas near the boundary of Zone 6, take precautions, as plants may not be reliably winter hardy throughout the northern portions of USDA Zone 5. Gardeners in regions like St. Louis should intentionally site Platycladus orientalis ‘Westmont’ where it is sheltered from harsh winter winds.

Maintenance is generally considered medium. Pruning is rarely necessary due to its inherent slow, tight growth habit; typically, only removing errant or damaged growth is required to maintain the desired upright-globular shape. Monitor regularly for potential insect pests that might affect the health of your Chinese arborvitae.

Landscape Uses

The compact stature of Platycladus orientalis ‘Westmont’ makes it immensely useful across various landscape applications. It excels as a small hedge, providing year-round definition without significant trimming requirements. Many homeowners utilize this evergreen as a primary foundation plant near buildings, where its size prevents obstruction of windows or siding.

Its unique texture and color also lend it well to being used as an accent specimen, breaking up large sweeps of lawn or contrasting nicely against broadleaf shrubs. Consider placing Platycladus orientalis ‘Westmont’ within borders where you need consistent green structure, or utilize it effectively when contained within attractive garden pots during the growing season.

When selecting companions, pair this needled evergreen with plants that offer contrasting foliage shapes or seasonal flower color. Low-growing perennials or flowering groundcovers that appreciate similar sun/moisture profiles create excellent visual depth beside the solid form of the Chinese arborvitae.

Standout Features

Noteworthy Characteristics

The species, Platycladus orientalis, commonly called oriental thuja or oriental arborvitae, typically grows much larger, often reaching heights of 18 to 25 feet as a conical tree or large shrub, developing reddish-brown bark and oval cones. However, the ‘Westmont’ cultivar is distinct; it is a compact, slow-growing, upright-globular form that puts on only about 2 inches of vertical growth per year, usually topping out around 26 inches tall by 18 inches wide in its first decade. Its scale-like foliage presents as dark green tipped with bright yellow, though this color may shift to a bronze hue during the winter months.

Potential Problems

Healthy, well-maintained plants sited in proper growing environments usually have few major problems, especially when given adequate drainage. Gardeners should watch closely for bagworms and spider mites, which commonly target conifers. Less frequently, scales, aphids, caterpillars, borers, and mealybugs may appear. Avoid planting Platycladus orientalis ‘Westmont’ in locations subject to heavy, wet snow, as branches may break under the significant snow weight during winter.

Tolerances

• Tolerates some light afternoon shade.

Frequently Asked Questions

What hardiness zones is Chinese arborvitae suitable for?

Platycladus orientalis ‘Westmont’ is generally hardy and reliably grown in USDA Zones 6 through 9.

How large does Platycladus orientalis ‘Westmont’ grow?

This compact cultivar grows slowly, typically reaching only 2 to 4 feet in height and a similar spread at maturity, though this can take many years.

What sun exposure does Chinese arborvitae need?

This needled evergreen requires full sun for the best, densest growth, but it will successfully grow where it receives part shade, particularly shelter from the hottest afternoon sun.

When does Platycladus orientalis ‘Westmont’ bloom?

This plant is categorized as non-flowering, meaning you will not observe traditional flowers; instead, it produces small, oval cones.

Conclusion

The Platycladus orientalis ‘Westmont’ is an outstanding choice for gardeners seeking year-round structure in a perfectly scaled package. Its slow growth and attractive dark green foliage tipped with yellow ensure this Chinese arborvitae remains an excellent, manageable specimen for borders or foundation use. Before planting, confirm your site falls reliably within USDA Zones 6-9 and ensure the soil drains well for long-term success.

Companion Planting

Choosing appropriate companions helps enhance the visual appeal of Platycladus orientalis ‘Westmont’ while ensuring favorable microclimates. Since this needs medium water and prefers well-drained conditions, pair it with other low-maintenance, drought-tolerant evergreens or perennials that thrive in similar morning sun situations. Consider contrasting textures by planting low mounds of ornamental grasses nearby; varieties like Hakonechloa macra (if moisture is consistent) or shorter Festuca selections can look stunning flanking the dense, upright form.

For color contrast, use deciduous plants that offer vivid spring or summer blooms against the static green background provided by the Chinese arborvitae foliage. Plants such as low-growing Spirea cultivars or compact Japanese maples (Acer palmatum varieties), provided they don’t cast deep shade, complement the year-round presence of Platycladus orientalis ‘Westmont’.

Seasonal Care Calendar

Spring is the ideal time for new plantings of Platycladus orientalis ‘Westmont’ once the threat of hard frost has passed. This is also when you should perform a light cleanup, removing any lingering winter debris from around the base of the plant. During the summer, focus heavily on consistent watering, especially if you experience extended dry spells, to maintain the medium moisture level required for healthy root development in your Chinese arborvitae.

In the autumn, cease supplemental deep watering as the plant prepares for dormancy. While this cultivar is moderately hardy, protecting plants established near the northern edge of Zone 6 from severe winter winds is prudent. Do not apply heavy mulch or fertilizers near the trunk late in the season, as this can encourage tender, new growth susceptible to freeze damage.