Thuja Emerald Trio Ball 20 Litre Pot 80-100cm High

Thuja occidentalis 'Smaragd' – Emerald Green Arborvitae
Thuja occidentalis 'Smaragd' is a slow-growing, narrowly columnar evergreen conifer prized above almost any other for the exceptional, jewel-bright green colour it holds reliably throughout the entire year. Where many conifers dull, bronze, or take on a yellowish cast through autumn and winter, 'Smaragd' remains a vivid, saturated emerald — the quality that gives this cultivar both its Danish name and its enduring popularity with gardeners seeking a specimen of genuine year-round distinction. Its refined, upright silhouette, naturally tidy habit, and restrained rate of growth make it equally well suited to formal hedging, accent planting, and structured garden design where precision and permanence are equally important.

Fully hardy, adaptable to a wide range of soils, and straightforward to maintain with minimal intervention, 'Smaragd' is a conifer that rewards patience with outstanding results. Whether planted as a crisp, formal screen, a pair of elegant sentinels flanking an entrance, or a repeated vertical accent in a mixed border, it brings a quality of evergreen permanence and refined colour that few other conifers can match.

Habit & Appearance

Form and foliage. 'Smaragd' develops a strongly upright, narrowly conical to columnar outline that remains elegantly well-defined as the plant matures, with very little tendency to spread or become misshapen over time. The foliage is carried in flat, fan-like sprays of fine, scale-like leaves with a pleasantly soft texture and the characteristic resinous fragrance of the Thuja family when brushed or clipped. The outstanding quality of this cultivar is the intensity and consistency of its foliage colour — a rich, deep emerald green that remains vivid and saturated through every season of the year, including the coldest winter months when the majority of comparable conifers fade noticeably. This exceptional colour retention is the defining characteristic that sets 'Smaragd' apart from almost every other hedging or screening conifer available. Left unpruned, plants will slowly build to a mature height of around 3–4 metres, maintaining their characteristic narrow form throughout.

Growth rate. 'Smaragd' is a slow to moderately growing conifer, typically putting on 15–25 cm of new growth per year under good conditions. This modest rate of growth is, in many situations, an advantage rather than a limitation — plants require far less frequent trimming than faster-growing alternatives and are far easier to keep at a specific size over the long term. The slower pace of growth also produces foliage of a notably dense, fine texture that contributes greatly to the cultivar's polished, refined appearance.

Growing Conditions

Position. Thuja 'Smaragd' performs best in a position receiving full sun to partial shade. It produces its richest, most consistent foliage colour in an open, bright aspect, though it tolerates dappled shade well and remains perfectly ornamental in less sunny positions. Fully hardy throughout the UK, it is sufficiently robust for most garden conditions, though it is best sited away from the most severely exposed or windswept locations where strong, desiccating winds may cause winter foliage scorch.

Soil. Adaptable to most fertile, reasonably well-drained soils, including clay, loam, and sandy ground. Like all Thuja, 'Smaragd' performs better in consistently moist conditions than in very dry soils, but will not tolerate permanent waterlogging or poorly drained ground. On heavier soils, incorporating organic matter and improving drainage at the time of planting will encourage stronger, healthier establishment and more consistent growth. A slightly acid to neutral soil pH is ideal, though the plant copes well with mildly alkaline conditions.

Planting spacing. For a dense, formal hedge, plant approximately 50–60 cm apart. This spacing will allow canopies to knit together in good time while maintaining the naturally narrow form that makes 'Smaragd' so effective for precise, space-efficient screening. For use as individual accent or specimen plants, allow sufficient space for the plant's full mature width — typically 60–80 cm — to develop without crowding from neighbouring planting.

Care

Watering. Regular, thorough watering throughout the first full growing season after planting is essential to allow the root system to establish securely. Pay particular attention during dry spells in spring and summer, when young plants are most susceptible to moisture stress. 'Smaragd' appreciates consistently moist soil conditions to a greater degree than some conifers, and maintaining adequate soil moisture — particularly in the first two to three years — will have a noticeable positive effect on the vigour and quality of growth. Once well established, plants become considerably more resilient and will generally require supplementary watering only during extended dry periods.

Feeding. Apply a balanced, slow-release granular fertiliser in early spring each year to support steady, healthy growth and to maintain the depth and vibrancy of the foliage colour. A feed formulated specifically for conifers or hedging plants is particularly well suited to this purpose. An annual mulch of bark chippings or garden compost applied around the base of the plants in spring will help conserve soil moisture, suppress competing weeds, and moderate root temperature through both summer and winter.

Pruning. One of the most practical qualities of 'Smaragd' is its naturally tidy, well-ordered habit, which requires very little trimming to remain looking its best. A single light clip once a year — ideally in late spring after any risk of late frost has passed, or in late summer — is generally all that is needed to maintain a crisp outline and encourage dense, even foliage coverage. For those growing 'Smaragd' as a formal hedge, two light trims per year will produce the sharpest, most uniform results. Always avoid cutting back hard into old, bare wood, as Thuja does not regenerate readily from stems that have lost their foliage. The slower growth rate of this