Thuja occidentalis compacta Seeds | Compact Arborvitae

Compact Arborvitae (Thuja occidentalis compacta) with dense flat sprays of deep-green scale-like foliage — Compact Arborvitae (*Thuja occidentalis* compact forms): Cupressaceae, the neat evergreen of the northern hedge.

LATIN NAME: Thuja occidentalis compacta

COMMON NAME: Compact Arborvitae

Plant Profile

The compact forms of the Eastern Arborvitae are dense, upright, slow evergreen shrubs of the cypress family, carrying their small scale-like leaves in flat, fan-shaped sprays that overlap like green roof tiles. Foliage stays deep green through winter when many conifers bronze, and the whole plant has the tidy, formal look that made its species the default hedge conifer of the American North and of northern European churchyards. Crushed, the sprays smell resinous and clean, a scent most gardeners recognise before they can name the plant.

The compact selections range from knee-high globes to narrow six-metre spires, and all of them share the species’ tolerance of cold, of damp heavy soil and of shearing to a line. They are among the few conifers that genuinely enjoy a wet clay winter.

Science & Biotechnology

Thuja occidentalis is a boreal species whose natural range runs from Nova Scotia to Manitoba, and its horticultural selections have been studied for cold hardiness, winter colour retention and response to shearing, research that sits behind the dozens of named clones in the trade. The species’ own history is entangled with early European exploration: scurvy-stricken sailors were saved by a vitamin-C-rich tea brewed from its foliage by First Nations knowledge, a story that earned it the name arborvitae, tree of life. The foliage oil is dominated by thujone, a compound with real toxicity, which is why the plant’s traditional internal uses have passed out of safe practice.

In much of suburban North America the plant’s chief research-relevant enemy is the white-tailed deer, which browse it to bare skirts wherever winters push deer into gardens.

Uses & Benefits

Its use is structural: hedges, screens, windbreaks, formal cones in pots, and the dark green walls that give a garden its rooms. Dense growth holds birds through winter, the foliage takes any amount of shaping, and the plant tolerates the damp, shaded, clay-bound corners where junipers and false cyprellas decline. As a specimen, a single compact form gives year-round presence on a fraction of the footprint of a broad conifer.

Foliage sprays are a traditional winter greenery for wreaths and garlands, and a clipped hedge of this plant is among the least demanding boundaries a garden can have.

Growing from Seed

Sow seed in spring after two months of cold, moist stratification, pressing it onto a free-draining compost and covering it thinly; germination is uneven, trickling over several weeks, and the tiny seedlings grow slowly at first. Keep the trays in bright, airy half shade and never let them dry out entirely.

Pot on each spring and shear lightly from the second year to build density from the base. Plant out in autumn or spring into any soil from sand to clay, in sun or part shade, spacing hedge plants at sixty to seventy centimetres. Water the first summer, then shear annually; protect young plants from deer where deer exist, because they will find it.

Our Take

The tidy hedge conifer of cold, damp gardens: green through winter, tolerant of clay and shears alike, and nearly indestructible once it has a root hold. Deer permitting.

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