Chamaecyparis obtusa 'Kosteri' (Kosters Falsecypress)


Michael's Opinion

A fine dwarf specimen that is well suited and incorporated into rock and pond gardens. It offers interesting twisting form and more vibrant colour then the original C. obtusa, but must be protected from strong winds in order to thrive. Kosteri rarely produces cones, so would be considered a horticultural achievement if cones occur.

Botanical Information

FamilyCupressaceae
GenusChamaecyparis
Speciesobtusa
Cultivar'Kosteri'
CategoryWoody
TypeShrub (evergreen)
Pronunciation

Details

USDA Hardiness Zone4b-8b
USDA Hardiness Ref.
Canadian Hardiness Zone4a
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Temperature (°C)hardy to -20
Temperature (°F)-30
Height1.5 m
Spread1.2 m
GrowthSlow
Flowering PeriodSeptember

Description and Growing Information

General DescriptionSlow growing dwarf retaining central main trunk, with flat, semi obtuse top in early growth stages. Produces very small, irregular scales along mostly flat stems.
ID CharacteristicStrange semi dense growth form exuding both vertically and horizontally twisting foliage along slightly drooped, pendulous branches. Also has distinct silver leaf scale margins, common with most C. obtusa cultivars.
ShapePyramidal, somewhat obtuse when young, loosely compact with horizontal uneven sprays.
LandscapeCan be effectively utilized in a Japanese style rock garden, as well as a focal point around ponds and pools. Kosteri can also be added to small patio container gardens and used in mixed border applications, as well as general city conditions.
PropagationTake earlier softwood cuttings between late June and September and root with bottom heat, and humidity of at least 73%. Can also be grafted from scion in late winter to early spring time, but does not retain same vigor and form. As cones are rarely produced, kosteri is usually not propagated from seed.
CultivationDoes well when protected from harsh dry winds. Likes regular watering during early stages of growth, but will withstand drought when mature. Will thrive if given an annual dose of nitrogen rich fertilizer in early autumn. Prefers well drained, moist, cool, slightly acidic to neutral soils. Will perform best in full sun, but can withstand moderate to partial shade. Does not respond well to pruning.
PestsTolerant of most pests. Somewhat prone to tip blight, spuce mites, and juniper scale. Susceptible to winter burn.
HabitatSubmontane evergreen forests of Japan.
Bark/Stem DescriptionBright red/orange brown furrowed to form trench like form. Thin and peeling, and delicate when young.
Flower/Leaf Bud DescriptionVery small shoots growing roughly 1-3 mm in size, insignificant, producing a dull grayish green/ orange like brown colour.
Leaf DescriptionBright mossy green, closely packed, small scale like, diamond shaped, netted, odorous and resinous, 2 mm. Can be somewhat rough/sharp to the touch.
Flower DescriptionCultivar rarely produces flowers. Those that do, produce small insignificant dull yellow diacious flowers on seperate branches.
Fruit DescriptionWill rarely produce cones. Those that do exibit very small, globose male cones, and more slender elongated female cones of grey colour averaging less then 2 cm with 2 to 8 wings.
Colour DescriptionMuch lighter shade of green than original C. obtusa. Retains silver leaf undersides. Bark has an interesting orange reddish tinge. Leaves produce redish bronze tinge in the winter months.
Texture DescriptionMedium textured, scales somewhat prickly and waxy. Bark is thin, smooth and peeling.

Photographs