Kousa Dogwood (Cornus kousa)

The kousa dogwood is known for its ornamental appeal. The showy flowers and bark, as well as the lovely fall foliage, make this vase-shaped tree a great addition to your patio, yard, or lawn. The tree matures to about 9 m high and is often just as wide.

I. Appearance and Characteristics 

Cornus kousa is a small deciduous tree 8–12 m (26–39 ft) tall, in the flowering plant family Cornaceae. Common names include kousa, kousa dogwood, Chinese dogwood, Korean dogwood, and Japanese dogwood. Synonyms are Benthamia kousa and Cynoxylon kousa. It is a plant native to East Asia including Korea, China and Japan. Widely cultivated as an ornamental, it is naturalized in New York State.

Like other Cornus, C. kousa has opposite, simple leaves, 4–10 cm long. The tree is extremely showy when in bloom, but what appear to be four, white petals are actually four spreading bracts below the cluster of inconspicuous yellow-green flowers. The blossoms appear in late spring, weeks after the tree leaves.

It can be distinguished from the flowering dogwood (Cornus florida) of eastern North America by its more upright habit, flowering about a month later, and by the pointed rather than rounded flower bracts.

Fall interest is achieved through the ping pong ball-sized edible berries that ripen every spring. The kousa berries are a visual delight and offer a delicious treat to the wildlife who use them as a nearly endless source of food before winter. These berries will attract birds, deer, small mammals, and possibly neighbors in the know who are interested in wine and jelly making. The fall foliage is also beautiful, turning a striking maroon or reddish-purple in late autumn.

The fruit is a globose pink to red compound berry 2–3 cm in diameter, though these berries tend to grow larger towards the end of the season and some berry clusters that do not fall from the tree exceed 4 cm. It is edible, with a sweet and creamy flavor, and is a delicious addition to the tree’s ornamental value. The fruit is sometimes used for making wine.

It is resistant to the dogwood anthracnose disease, caused by the fungus Discula destructiva, unlike C. florida, which is very susceptible and commonly killed by it; for this reason, C. kousa is being widely planted as an ornamental tree in areas affected by the disease.

II. How to Grow and Care

Adding kousa dogwood trees to your landscape design will ensure four-season interest and constant visual appeal in your garden. To achieve this year-round appeal, however, does take some work. Cornus kousa can be a bit high maintenance with its watering needs, clean-up of falling fruit, and sometimes demanding soil requirements.

Sunlight

Kousa dogwood prefers full sun and can grow in a slightly shaded environment. It needs 4-6 hours of sunlight per day; if it does not get enough sun, the plant will grow poorly, the branches will become lighter in color, and the number of flowers and fruit will be fewer.

Temperature and Humidity

Trees with shallow root systems benefit from a few inches of mulch to moderate the soil temperature. The kousa is one of these shallow-rooted trees. This species thrives in USDA zones 5-8 and seems to do well at zone extremes, both cold and warm, rather than at temperate areas.

Watering

Water kousa dogwood 1-2 times a week. In hot summer or sunny conditions, appropriately increase the watering frequency. When the plant is dormant in winter, it absorbs water at a reduced rate, so you will need to reduce the amount of watering. When watering, be careful not to spray water on the leaves, as too much water on the leaves can cause pests and diseases.

Soil

The kousa will thrive in rich soils with plenty of organic materials that are consistently moist but not wet. If placed in soils with a high pH, the kousa may develop light foliage, a sure sign that the tree lacks soil acidity, which it prefers.

Fertilizing

Kousa dogwood does not require much fertilizer. Too much fertilization can lead to excessive growth and weaker resistance. If the soil is poor, add a decomposing organic fertilizer in spring. If you want the tree to bloom and flourish, add some potassium fertilizer. Do not apply fertilizer in the first year of planting, because it may damage the newly grown root system. You can apply fertilizer after one year of growth.

Planting Instructions

You can transplant kousa dogwood from a pot into a garden anytime throughout the year. If you plan to transplant a seedling with bare roots, do it at the end of fall or early spring to avoid the frost. When transplanting, the planting hole should be wide enough to allow room for the roots to grow. plant at a depth of two-thirds of the soil ball, so the covered soil is slightly above the ground, which helps drainage. Water the soil well to keep it moist after planting. You can also cover the soil surface with mulch to reduce water evaporation and keep the soil cool.

Pruning

Kousa dogwood does not require much pruning. You need only to cut off dead, injured branches and any parts infected with pests and disease. Prune kousa dogwood in late fall and winter. If you prune it in spring or summer, the plant is in its growing season and the wounds will shed a lot of sap; in late fall and winter, kousa dogwood enters dormancy and will not do that.

Propagation

As with most species of Cornus, it’s best to propagate C. kousa from seed, by taking stem cuttings, or via transplanting.

These methods are listed here in order of descending difficulty. See our guide to growing flowering dogwood for general propagation information.

Propagating from seed definitely takes the longest, but the potential rewards are the greatest, since you could end up with a unique and desirable mutation.

Transplanting is best for those who have a ready-to-transplant specimen on hand and/or want a kousa dogwood ASAP, while cuttings are the middle-of-the-road option for folks who want to grow the plant from infancy, but wish to bypass the seed gathering, stratification, and germination steps.

Let’s touch on some specific aspects of kousa dogwood propagation, real quick.

First off, the fruits: rather than producing a cluster of red, olive-shaped berries that ripen in August like the flowering dogwood does, C. kousa has spherical, spiky fruits that hang from stems and finish ripening by mid-September.

Additionally, its seeds are a bit bulkier and more irregularly-shaped than those of C. florida.

It’s actually quite easy to pop open the fruits with your hands to get at the seeds within, which will need to be stratified for 120 days prior to sowing indoors.

Stem cuttings should be harvested in four-inch lengths from semi-hardwood shoots come summer, and given a basal dip of root hormone to speed up the rooting process before sticking in growing media, growing indoors, and hardening off outside come spring.

As far as transplants go, you’ll want to place them in fertile and well-draining planting sites, with a pH of 5.5 to 6.5.

Make sure the sites are situated at least 20 feet away from each other, and at least six feet away from natural hardscapes and man-made structures.

Pests and Diseases

One of the best traits of C. kousa is its resistance to pests and pathogens.

Common Cornus issues such as anthracnose, powdery mildew, and dogwood borer infestations are not a problem for this tree.

Using sterilized gardening tools, disease-free plants, and clean soil are all wise ways of preventing potential problems, of course.

Selecting cultivars renowned for their resilience is another smart strategy.

But for the most part, a C. kousa doesn’t require the concern over infestation and infection that, say, a C. florida specimen would.

Be sure to select an appropriate planting site with adequate sun exposure and soil drainage to avoid issues with rot, and to promote flowering.

III. Uses and Benefits 

• Culinary uses

kousa has edible berries. The soft pulp is sweet with a similar flavor to a ripe persimmon but the presence of hard seeds that are well attached to the pulp can be inconvenient when eaten directly. The rind of the berries is usually discarded because it has a bitter taste, although it is edible. The seeds are usually not eaten, but could be ground into jam and sauces. While less popular than the berries, young leaves can also be consumed.

• Ornamental uses

Kousa dogwood is gorgeous enough to pose as a specimen in the landscape – it’s a one-plant show. But when planted in multiples and arranged in a line, these trees make for a solid and aesthetic border. It’ll certainly look better than a wall or fence, if I do say so myself!

As a foundation planting, this tree’s horizontal branching pairs quite nicely with the vertical lines formed by the corners and edges of buildings, making the man-made structures somehow appear larger.

And it goes without saying that a C. kousa is the perfect planting for those who want the dogwood aesthetic sans any significant pest and disease risk.