Thuja occidentalis 'Smaragd ' (Emerald or Smaragd Cedar)

Michael's Opinion

This very hardy, slow growing, compact tree would be a perfect addition to any landscape because it rarely needs pruning or much attention. Perfect in every season because it holds its bright lustrous emerald green foliage all year round.

Botanical Information

Cultivar'Smaragd '
SynonymsThuja occidentalis 'Emerald'
TypeShrub (evergreen)
OriginIntroduced by D. T. Poulsen of Denmark. Smaragd comes from the Greek language and is in reference to the plants emerald green colour.


USDA Hardiness Zone4
USDA Hardiness Ref.
Canadian Hardiness Zone5-8
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Temperature (°C)-40
Temperature (°F)-50
Height2-3 m
Spread70-90 cm
Flowering PeriodMay

Description and Growing Information

General DescriptionCompact, evergreen, pyramidal tree that retains its glossy, bright green foliage throughout the year, making it a valuable hedge plant or specimen. Tolerates a wide range of soils and likes humid conditions with regular precipitation.
ID CharacteristicEmerald-green, dense, pyramidal evergreen. Holds its colour nicely all year. Rarely needs pruning. Excellent hedge plant. Shows excellent heat and cold tolerance.
ShapeNarrow, compact, pyramidal form.
PropagationTake cuttings from current seasons wood with a heel from November onwards through early March. Root in perlite/peat/3/1 with about 4000 ppm of KIBA with bottom heat and mist.
CultivationGrows in part/full sun; likes clay, loam, sandy soil which can be slightly alkaline to acidic. Soil must be well drained. Has moderate drought and salt tolerance but is tolerant of walnuts.
PestsCaterpillars, bark beetles, weevils, mites and scale insects are common, as well as butt rot, twig dieback, Borytis, mushroom root rot and needle blight.
Notable SpecimensThe Gardens of Fanshawe College, London, Ontario, Canada.
HabitatHorticultural origin.
Bark DescriptionBrown to grey-brown in colour, plated and not particularly showy. Furrowed into relatively narrow strips.
Bud DescriptionSmall, light brown cones with thin overlapping scales, approximately 1 cm in length.
Leaf DescriptionApproximately 2.5 cm in length. Bright green, scale-like, yet soft foliage in more or less vertical sprays that are arranged in an opposite pattern. They are also quite flexible and glabrous.
Flower DescriptionSpring flowering, yellow, inconspicuous and not showy. Borne singly and at the branch tips.
Fruit DescriptionOval shaped brown coloured fruit that is dry or hard and ripe from August to September. The fruit length is 2.5 cm. Does not attract wild life and is persistent on the tree.
Colour DescriptionBright, glossy, lustrous emerald green foliage, although there is also a gold-marked variegated sport of ‘Emerald’.
Texture DescriptionScale like, medium to fine foliage. Medium to rough bark. Smooth seeds.