Species Overview
Eastern white cedar (Thuja occidentalis) is a medium-sized evergreen conifer native to eastern Canada, ranging from Nova Scotia and New Brunswick through Quebec and Ontario as far west as southeastern Manitoba. In natural stands it is most commonly found along stream banks, lakeshores, cliff faces, and in low-lying areas with calcareous soils and high soil moisture — habitats that most other tree species avoid.
On rocky cliff faces in Ontario and Quebec, individual specimens have been documented as more than 1,000 years old — among the oldest known trees in eastern Canada — despite growing in extremely limiting conditions. The species achieves this longevity through slow, conservative growth rather than rapid resource acquisition.
In residential use, the cultivated form sold most commonly at Canadian nurseries is a compact, columnar cultivar ('Smaragd' or 'Emerald Green') bred for uniform hedging. This cultivar is genetically derived from the species but differs significantly in growth habit and cold hardiness from wild-type specimens.
Site Tolerances
Soil and Moisture
Wild eastern white cedar is most commonly associated with calcium-rich, moist to wet soils — particularly the thin, highly calcareous soils over limestone found throughout the Canadian Shield and Niagara Escarpment. However, the species also establishes on drier upland sites when competing vegetation is reduced.
In residential contexts, eastern white cedar is one of the few native conifers that handles periodic waterlogging without significant root damage. This makes it genuinely useful on low-lying properties, near drainage swales, or on sites where drainage improvement is not practical.
Cold Hardiness
The species is rated to Zone 2b — among the coldest of any native Canadian tree. In practice, the cultivar forms sold for hedging are often less cold-hardy than the wild type. 'Smaragd' performs reliably to Zone 4–5. Wild-type seedlings sourced from northern Ontario or Quebec seed collections will perform significantly better in Zones 2–3 than nursery stock of unspecified provenance.
Shade
Moderate shade tolerance in youth, declining as the tree matures. In dense shade, eastern white cedar becomes leggy and loses interior foliage density. For hedging applications requiring dense, uniform coverage, a minimum of 4–5 hours of direct sun per day is necessary to maintain consistent foliage from base to crown.
Deer Browsing
Eastern white cedar is among the most heavily browsed native trees in Ontario and Quebec. White-tailed deer browse the foliage intensively in winter, and in areas with significant deer pressure, natural cedar regeneration is effectively suppressed — a well-documented factor in the understory composition of forests across southern Ontario.
On residential properties, newly planted cedar hedge stock typically requires physical protection (tree tubes, wire enclosures, or mesh guards) for the first 2–3 years in areas with deer access. Once stems reach 5–6 cm diameter and foliage extends above typical browse height, browsing pressure decreases substantially.
Planting for Hedging
Eastern white cedar is the dominant species used for residential privacy hedging in Ontario and Quebec, with several million cultivar specimens planted annually. The standard spacing for a dense hedge is 45–60 cm between plants for a single row, or a staggered double row at 60 cm between rows and 90 cm between plants within each row.
Container-grown nursery stock (typically sold in 1- to 5-gallon containers) transplants reliably in spring or early autumn. Bare-root seedlings of the wild type are available through conservation authority programs at lower cost but require more careful establishment management in the first season.
Common Hedging Mistakes
- Planting too close: A 45 cm spacing will produce a dense hedge by year 5–7 but may require removal of every other plant by year 15 as crowns compete. Initial 60 cm spacing produces a slower-closing hedge that is more sustainable long-term.
- Shearing into a top-heavy profile: Wide-top, narrow-base hedges shade out lower foliage, producing a bare lower half that cannot recover. Always shear to a slightly tapered profile with the base wider than the top.
- Planting in standing water: While eastern white cedar tolerates saturated soils better than most conifers, persistently anaerobic conditions at the root zone still cause root decline. Drainage does not need to be perfect, but water should move through the root zone within 24–48 hours of rainfall.
Wildlife Value
In natural stands, eastern white cedar provides critical winter thermal cover for deer, moose, and a range of small mammals. Dense cedar stands create microclimates 2–4°C warmer than surrounding open areas on cold nights — a meaningful advantage for wildlife energy budgets in winter. The small, scale-like foliage provides nesting substrate for ruby-crowned kinglets and several species of warbler during migration and breeding periods.
The seeds are small and not a primary food source for most birds, but the dense foliage structure provides roosting cover for species including American robin, mourning dove, and various sparrow species through the winter months.
Ecological Restoration Use
Eastern white cedar is increasingly used in ecological restoration projects on calcareous lakeshores, cliff-edge habitats, and areas of the Niagara Escarpment where natural regeneration has been suppressed by deer browsing and invasive shrubs. Conservation projects typically use locally sourced seedlings to maintain genetic adaptation to regional conditions.
On private properties, planting eastern white cedar along fence lines and property boundaries creates habitat connectivity — particularly valuable in fragmented suburban and exurban landscapes where linear habitat corridors support wildlife movement between larger woodlot patches.
Distinguishing Wild-Type from Cultivars
Wild-type eastern white cedar has a broader, more irregular crown form, slightly drooping branch tips, and small, oval cones approximately 8–12 mm in length. The foliage scales are typically yellow-green in summer, bronzing slightly in cold weather. Cultivar forms ('Smaragd', 'Brandon', 'Techny') are selected for consistent upright form, uniformly green winter colour, and compact growth rate. For ecological restoration, wild-type seedlings are significantly more valuable than cultivar stock; for privacy hedging, the cultivars are more predictable.
External references: Trees Ontario · Natural Resources Canada — Forest Report · International Society of Arboriculture