American arborvitae (Thuja occidentalis 'Rheingold')

Overview

Thuja occidentalis ‘Rheingold’ stands out as a highly desirable, slow-growing dwarf cultivar of the well-known American arborvitae. Its primary feature is the dense, cone-shaped to dome-shaped habit crowned with striking, bright golden foliage that provides year-round color interest. This cultivar maintains a compact stature, making it an excellent structural accent where space is limited or where a bold, colorful specimen is needed.

As an evergreen, this variety of American arborvitae offers consistent texture and color, shifting to an attractive bronze-yellow hue during cold winter months. It is famed for its low maintenance requirements, appealing to both novice and experienced gardeners seeking reliable performance in USDA Zones 2 through 7. The natural shape of Thuja occidentalis ‘Rheingold’ minimizes the need for intensive pruning.

Ultimately, this plant provides reliable structure and year-round vibrancy, distinguishing itself from the taller, wilder forms of the species. Its compact size ensures it remains a manageable feature near foundations or within rock gardens, serving as a low-maintenance focal point throughout the growing season and beyond.

Fast Facts

• Plant Family: Cupressaceae
• Plant Type: Needled evergreen
• Hardiness Zones: USDA Zones 2-7
• Size at Maturity:
  • Height: 3-5 ft
  • Spread: 3-5 ft
• Bloom Time: Non-flowering
• Bloom Description: Non-flowering
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Low

How to Grow

The best time for planting Thuja occidentalis ‘Rheingold’ is typically in spring or early fall, allowing the root system to establish before extreme temperatures arrive. While this American arborvitae exhibits some soil tolerance, it performs optimally when planted in average, medium moisture, well-drained loams, preferably with a neutral to alkaline pH. Ensure the planting site receives full sun for the best golden color, though light afternoon shade is beneficial in hot summer climates to prevent scorching.

Watering should be consistent, aiming for medium moisture levels, especially during the first year after planting. Thuja occidentalis ‘Rheingold’ is intolerant of dry conditions, so regular deep watering is crucial during dry spells. Fertilizer is rarely necessary for established specimens, given its low maintenance classification, but a balanced, slow-release fertilizer applied in early spring can support vibrant new growth.

Pruning is generally minimal for this dwarf cultivar, as it naturally maintains a pleasing cone or dome shape. If shaping is desired, light shearing can be performed in late winter or early spring before new growth hardens off. Always avoid planting in exposed, windy sites, as these locations increase the risk of foliage burning in winter or stem breakage from heavy snow and ice accumulation.

Landscape Uses

The compact design and striking golden foliage make Thuja occidentalis ‘Rheingold’ an ideal choice for detailing and foundation plantings where larger evergreens would overwhelm the structure. Because it matures to only 3 to 5 feet tall and wide, it fits perfectly into defined borders or as foreground interest against taller backdrop shrubs. Its upright, dense habit also makes it an excellent specimen plant in rock gardens, mimicking the appearance of miniature conifers in alpine settings.

Consider grouping three or five specimens of Thuja occidentalis ‘Rheingold’ together to create an instant, low-growing hedge or screen effect along a walkway, providing year-round structure. Pair its bright gold tones with contrasting deep green or dark purple foliage plants, such as Dwarf Japanese Holly or dark-leaved Heuchera, to maximize visual drama in mixed borders. It provides necessary evergreen contrast throughout the winter landscape.

Standout Features

Noteworthy Characteristics

Thuja occidentalis, commonly known as American arborvitae, Eastern arborvitae, Eastern white cedar or Northern white cedar, is a dense, conical to narrow-pyramidal (sometimes maturing to broad-pyramidal), often single-trunked, evergreen tree that is native to eastern and central Canada south to northern Illinois, Ohio and New York with scattered populations further south in the Appalachians to North Carolina. Mature trees may reach 40-60’ tall in the wild over time, but in cultivation typically grow much smaller to 20-30’ tall. Scale-like, aromatic, yellow-green to green foliage appears in flattened sprays. Red-brown bark will exfoliate on mature branches and trunks. Genus name is the Greek name for a kind of juniper (Juniperus.) Specific epithet means from the Western (Occidental) world. The common name of arborvitae (tree of life) comes from early French settlers to North America who learned from Native Americans that the tree’s foliage could be used to treat scurvy. ‘Rheingold’ is a slow-growing, cone-shaped to dome-shaped, dwarf cultivar that typically matures to only 3-5’ tall. As the cultivar name suggests, it is noted for its bright golden foliage. Foliage is scale-like and appears in flat, fan-shaped clusters. Foliage turns bronze-yellow in winter.

Tolerances

• Clay Soil
• Black Walnut
• Air Pollution

Potential Problems

Leaf blight can cause foliage spotting and premature drop, which may require monitoring, especially in humid conditions where air circulation is poor. Gardeners should also watch for signs of canker, a fungal disease that attacks vulnerable stems and trunks. Keeping the area around the base of your Thuja occidentalis ‘Rheingold’ clean and well-ventilated is crucial for prevention.

Occasionally, this American arborvitae can attract minor pests like bagworms, mealybugs, scales, or spider mites. Inspect the densely layered foliage regularly, particularly the interior. If infestations are found, horticultural oils or insecticidal soaps are usually effective treatments for these occasional visitors to the foliage of your Thuja occidentalis ‘Rheingold’.

Winter conditions pose a threat, as exposed locations can lead to winter burn, turning the golden foliage yellow-brown. Furthermore, the brittle nature of the branches creates susceptibility to breakage from heavy ice and snow loads, so gently brushing off accumulated moisture is a necessary winter precaution for this cultivar.

Frequently Asked Questions

What hardiness zones is American arborvitae suitable for?

This cultivar, Thuja occidentalis ‘Rheingold’, is robustly hardy across USDA Zones 2 through 7.

How large does Thuja occidentalis ‘Rheingold’ grow?

It is a dwarf variety, typically maturing to a height and spread between 3 and 5 feet.

What sun exposure does American arborvitae need?

For the best color and density, Thuja occidentalis ‘Rheingold’ requires full sun to part shade; avoid deep, full shade entirely.

When does Thuja occidentalis ‘Rheingold’ bloom?

This plant is classified as non-flowering; it produces scale-like foliage rather than ornamental blooms or fruit.

Conclusion

The dwarf size, reliable evergreen nature, and exceptional golden color confirm that Thuja occidentalis ‘Rheingold’ is a cornerstone plant for color and structure in smaller landscapes. Gardeners value this American arborvitae for its low demands and high visual impact through all four seasons. Confirm your local USDA zone compatibility and plan to plant during cooler times of the year for the best establishment of your new Thuja occidentalis ‘Rheingold’.

Companion Planting

When selecting companions for Thuja occidentalis ‘Rheingold’, focus on plants that thrive in similar medium moisture conditions and can tolerate neutral to alkaline soil. Utilize contrasting textures and colors to highlight the golden foliage. Cool-season annuals like dark purple pansies planted directly beneath the shrub create an immediate, striking border, especially when the Thuja turns bronze in winter.

For perennial partners, consider plants that enjoy partial shade, as they will benefit from the slight afternoon protection the arborvitae can provide while thriving in the same moisture regimes. Hostas with blue or dark green variegation offer excellent textural counterpoint without competing aggressively for nutrients, provided they are kept slightly drier than plants requiring consistent moisture.

Consider low-growing groundcovers that thrive in similar pH ranges but offer a different growth habit. Hardy creeping phlox or Ajuga reptans can soften the base of the plant and cover any bare soil, enhancing the overall manicured look achieved by using a dwarf specimen like this American arborvitae.

Design Ideas

This slow-growing selection excels as an accent piece rather than a screen. Use it solitarily at a corner of a structure or entryway to provide architectural interest that minimizes the need for pruning maintenance. Its small scale allows it to function well in contemporary or formal container arrangements for patios, often paired with upright grasses or trailing evergreens for textural variance.

In Japanese-inspired gardens, Thuja occidentalis ‘Rheingold’ can represent a cloud-pruned specimen due to its naturally mounding habit, even with minimal intervention. Place it near water features or gravel beds where its bright hue can reflect ambient light, enhancing the serene atmosphere of the garden space.

For year-round screen possibilities, consider mass planting groups of three or five in a tight, triangular formation in a low border setting, such as along a primary pathway transition. Ensure adequate spacing based on its mature spread of up to 5 feet to prevent overcrowding, which can lead to reduced air circulation and increased susceptibility to blight.