Chinese dogwood

Family

Cornaceae

Habit

Tree

Height

9 m

Spread

6 m

Growth

slow

Lifespan

90 years

First yield

after 6 years

Full yield

after 30 years

Yield per plant

up to 15 kg a year

Yield in cultivation

up to 4 t/ha

Energy yield

500 kcal per m² a year

Hardiness

zone 5–8

Shade tolerance

partial shade

Soil

Sand, Silt, Loam, Clay

Soil moisture

dry – moist

pH

5.5 – 7.5

Synonyms

Blumenhartriegel, Fruchthartriegel,

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: Fruit can be enjoyed raw or cooked, being sweet and juicy in small amounts. While the skin is tough and unappealing, the flesh is delicious with a pudding-like texture, making it a favorite late summer fruit. The fruit is approximately 2 cm in diameter. Young leaves can also be cooked.

Medicinal: No medicinal use is documented for kousa dogwood. It should not be confused with the related Cornus officinalis, whose dried fruit flesh is used in traditional Chinese medicine as shan zhu yu; those records do not apply to Cornus kousa.

Other uses: The wood of kousa dogwood is exceptionally hard, heavy and tough, as dogwood timber generally is. In East Asia it goes into mallets, tool handles, wedges and fine turnery; the trunks are too short and too crooked for construction. Most of its value today lies in ornament: the white bracts stand above the foliage from May into July, the leaves turn wine-red to scarlet in autumn, and older trunks shed their bark in light and dark brown plates that give the shrub structure through the winter too. In Japan and China it is a traditional temple and garden tree. In Europe it was long treated as a pure ornamental even though the fruit is good to eat — a misunderstanding the wild-fruit movement is only now undoing.

Site: The decisive factor is lime — kousa dogwood will not take it. Limestone chippings in the subsoil, builders' rubble against a house wall, mortar residue or hard tap water all lead to iron-deficiency chlorosis, with pale leaves and green veins. What it needs is humus-rich, evenly moist, acid to slightly acid soil in sun to light partial shade. It reaches three to six metres in height and width, more in good positions, and grows slowly; even so, give it generous final spacing, because it takes pruning badly. The fruits drop in September and October and crush into sticky red marks on paving and terraces — do not plant it over a seating area or path. If you want a crop, choose a warm position: in cool regions the fruit often fails to ripen. Care: Best of all, do not prune. Kousa dogwood flowers on wood several years old, builds its tiered crown over time and answers hard cutting back with bare patches; remove only deadwood and inward-growing shoots. It roots shallowly, so do not hoe the root zone — mulch it with leaves, bark humus or conifer litter, which also keeps the pH down. Water evenly in dry spells, preferably with rainwater; drought stress shows as browning leaf margins. Feed only with acidifying products. Nothing needs doing about anthracnose, which barely touches this species while it damages Cornus florida severely. Young plants get a mulch layer over the rootball for their first winters; established shrubs are hardy to about -28 degrees. Birds will take a share of the ripe fruit.

Kousa dogwood is easy to raise from seed, but slow. Collect ripe fruit in October and rub and wash the flesh off carefully, since it contains germination inhibitors. The seed then goes either straight into a sheltered outdoor bed or, after four to five months of cold stratification at about five degrees, into pots; it not uncommonly comes up only in the second spring, so leave the seedbed standing. Seedlings take six to ten years to flower and vary in fruit size and flavour. Named cultivars and fruiting selections are therefore grafted, usually as a winter bench graft onto seedling rootstocks of the same species. Semi-ripe cuttings taken in July under mist root acceptably, but must push new growth the same year or they winter badly. Low branches can be layered.

Kousa dogwood is an East Asian introduction with limited but not negligible value. What looks like one large white flower is a set of four bracts; the true flowers sit in the middle as an inconspicuous greenish head and offer only modest nectar and pollen. The tally is correspondingly sober: about three wild bee species are documented as visitors in Central Europe, none of them specialists. Its performance as a structural and food shrub is considerably better. The dense, tiered branching carries nests, and the soft red compound fruits ripen in September and October, just as blackbirds and thrushes are laying in reserves for migration. Adding a cornelian cherry or common dogwood to the same garden brings the native insect side along with it.

Special features: Sensitive to prolonged drought (see shallow rooting); best pruned during flowering. Flavor varies by variety; well-known varieties include 'Milky Way,' 'China Girl,' 'Big Apple,' and 'Norman Hadden.' The latter is a cross with Cornus capitata (larger fruits, but less frost-hardy). Cornus kousa is generally less fruitful.

East Asia: Japan, Korea and China. Kousa dogwood occupies the mountain forests of Japan from Honshu to Kyushu and the Korean peninsula; the large-fruited variety var. chinensis comes from mainland China, where it ranges from Sichuan through Hubei to Zhejiang and climbs to around 2,200 metres. The species reached Europe and North America in the nineteenth century as an ornamental. In China it has long been valued as a fruit tree as well, whereas in Europe it was planted almost solely for its flowers. It has not naturalised in Central Europe and remains tied to gardens, parks and nursery catalogues.

In its homeland kousa dogwood is a tree of the second canopy layer and of woodland edges in mountain forest. It grows in valleys, on shaded slopes and along streams and forest tracks, in open and closed mixed and broadleaf woodland alike, in China between roughly 400 and 2,200 metres. The soils there are humus-rich, evenly moist and acid to slightly acid — the species is decidedly lime-avoiding and absent from shallow limestone. It tolerates partial shade well and still flowers reliably there, which is why its characteristic place is beneath the open crowns of other trees. Waterlogging and summer desiccation limit its occurrence.