Kousa Dogwood, Japanese Dogwood, or Chinese Dogwood

(Cornaceae - Dogwood Family)

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• Form
  • small deciduous ornamental tree
  • maturing at about 20' tall by 20' wide
  • upright vased growth habit in youth, with branches becoming horizontally layered with age
  • slow growth rate

• Culture
  • full sun to partial shade
  • prefers moist, well-drained, acidic soils in partial sun, but is adaptable to dry soils, compacted soils, and neutral to alkaline soils; needs irrigation during the hot, dry periods of Summer, to lessen the degree of leaf scorch that may occur, especially on trees transplanted within the last three years that are re-establishing
  • propagated by rooted cuttings, cultivar cuttings grafted onto seedling rootstock, or seeds
  • Dogwood Family, with no serious disease or pest problems
  • abundantly available, in ball and burlap or container form
  • much more pH adaptable to alkaline pH soils and is often more tolerant of dry soils than is Flowering Dogwood (Cornus florida), its more popular counterpart
  • Kousa Dogwood is somewhat sensitive to being transplanted in Autumn, and care should be taken to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray, to enhance survival chances during the first Winter (this advisory is less critical for those shrubs transplanted from containers, rather than root-pruned ball and burlap specimens)

• Foliage
  • medium to dark green, to 3" long, often having scorched leaf tips and leaf margins by late Summer if sited in full sun, if re-establishing after transplanting, or following especially prolonged dry periods
  • opposite, broad elliptic, sometimes with undulating leaf margins, with the major leaf veins parallel to the curving leaf margins
  • fall color ranges from an inconsistent reddish purple (in full sun) to green or chartreuse (in partial shade)

• Flowers
  • the true flowers (which are ornamentally insignificant) are small yellow-green inflorescences centered among the four showy white bracts, the latter of which are obovate and distinctly acuminate, with the diameter of the entire inflorescence being about 3" wide
  • inflorescences are prominently lifted above the stem and branch plane by 2" tall verticle peduncles, somewhat similar to the floral arrangement found in Doublefile Viburnum (Viburnum plicatum tomentosum)
  • flowering in June and early July, with a four- to six-week bloom period, including the early period when the bracts are small, lime-colored, and expanding

• Fruits
  • globular green fruits turn to pink, then dull red in September, resembling large solitary upright raspberries on a 2" peduncle (fruiting stalk)
  • intriguing in contrast to the green foliage, but fruit set is usually light, being sparsely scattered above the foliage, and readily eaten by birds and squirrels when ripe

• Twigs
  • tan to dark brown and very slender, with numerous lenticels
  • vegetative buds are thin and conical, while the floral buds are pointed and oval, with the two floral bud scales slightly separated at the edge of the bud

• Trunk
  • multi-trunked, or single-trunked with very low branching
  • light brown-gray trunks are interrupted by smooth yellow-beige or dark gray-white blotches that make the bark rather ornamental with age
  • bark becomes more mottled and ornamental if the lower branches of the tree are removed with maturity, exposing the lower trunks to more light

• ID Summary
  • leaves are elliptical with slightly undulating leaf margins and leaf veins parallel to the leaf margins, while the flowers are the primary ornamental feature, being later flowering than all other Dogwoods (in June and into early July), with four showy outer bracts that have pointed apices (rather than indented ones, as in Flowering Dogwood)
  • fall color, when the tree is sited in full sun, is faded shades of brick red or red-purple, while the bark becomes ornamental with age, a mixture of cream and gray splotches, and more smooth than exfoliating

• Function
  • specimen, foundation, entranceway, border, understory, focal point, or seasonal accent small tree

• Texture
  • medium texture in foliage and medium-fine texture when bare
  • thick density in foliage and when bare

• Assets
  • small ornamental tree with four-season appeal (foliage, flowers, fruits, bark, shape, and bark)
  • very long-lasting and showy flowers, blooming in late Spring and early Summer
  • vased growth habit, becoming arching and layered with age
  • ornamental bark with age
  • superior disease/pest resistance among the showy-flowering Dogwoods

• Liabilities
  • not especially tolerant of urban stresses (but usually more so than Flowering Dogwood)

• Habitat
  • zones 5 to 8
  • native to the Orient

• Alternates
  • trees with showy flowers and ornamental bark (Cercis canadensis, Chionanthus retusus, Cornus florida, Crataegus viridis 'Winter King', Franklinia alatamaha, Prunus serrulata, Stewartia ovata, Syringa reticulata, etc.)
  • vase-shaped companion trees (Crataegus viridis 'Winter King', Prunus serrulata 'Kwanzan', Ulmus americana 'Delaware', Zelkova serrata, etc.) or shrubs (Euonymus alatus, Viburnum plicatum tomentosum 'Mariesii', etc.)

• Variants
  • Cornus kousa 'Gold Star' - variegated foliage has a central golden stripe, which reverts to green by late Summer
  • Cornus kousa 'Lustgarten Weeping' - a weeping form often grafted onto a 2' to 5' standard, spreading to 15' wide and 3' high (above the graft), with flowers prominently viewed along the arching, pendulous stems
  • Cornus kousa 'Madame Butterfly' - bracts curve upward, giving the appearance of white butterflies in flight when in bloom
  • Cornus kousa 'Moonbeam' - flowers 7" in diameter instead of the normal 3"
  • Cornus kousa 'Satomi' - faded pink flowers
  • Cornus kousa chinensis 'Milky Way' - much heavier flower and fruit production, and the most common cultivar
  • Cornus x rutgersensis 'Constellation' - white flowering hybrid of Kousa and Flowering Dogwoods, resistant to the borers and anthracnose that sometimes plague Flowering Dogwood
  • Cornus x rutgersensis 'Stellar Pink' - similar to the above hybrid, but pink flowering

• Translation
  • Cornus is the Latin name for Dogwood.
  • kousa is the Japanese name for this tree.

• Purpose
  • Kousa Dogwood is an alternative to Flowering Dogwood (Cornus florida), with a later and longer bloom period, virtually no disease or pest problems, and alkaline soil tolerance.

• Summary
  • Cornus kousa is a multi-season small tree, noted for its early Summer long-lasting flowers, Autumn fruits, good Summer foliage and occasional fall color, Winter bark, layered branching, and vased growth habit.