Taxonomy and origin
Dogwood is the common name for the genus Cornus, and the tree most Americans mean by it is the flowering dogwood, of the family Cornaceae. It is native to eastern North America, from Maine to southern Ontario to Illinois to Kansas and south to Florida, Texas and Mexico, and grows nowhere in the Old World except where somebody planted it. Missouri alone holds five species of the genus. It is state tree of Missouri and Virginia and state flower of North Carolina. The genus name comes from the Latin for horn, a nod to the strong dense wood, and the common name probably traces to old skewers cut from the hard slender stems, once called dags or dogs.
The showy part of a dogwood is a ring of four bracts, modified leaves that do the work of petals. Inside that ring sit 25 to 30 small true flowers, yellowish green and packed into a button at the center. Open and flat, the four bracts read from a distance as one white flower 3 to 4 inches across, though a single bract measures 1 1/4 to 2 1/2 inches long. Two details identify the genus once the flowers are gone: leaf veins that curve toward the tip and stop short of the margin, and branches layered in flat horizontal tiers, clearest on flowering and kousa dogwoods in shade.
Several other dogwoods account for most of what is sold. Kousa comes from Japan, Korea, China and Taiwan, and its species name is the Japanese name for the plant. Pacific dogwood is the western tree, running along the coast and about 200 miles inland from past Vancouver Island to southern California, with an outlying population in north-central Idaho. Cornelian cherry dogwood is a European and Asian species, multi-stemmed and shrubby. The last group is not a species: the Rutgers hybrids, crosses of flowering dogwood and kousa sold under several cultivar names.
Bloom time
Flowering dogwood blooms in spring, most often across April and May, on a national calendar that runs from mid-March in the South to late May in the North. The bracts open before the leaves, which is why the flat white flowers carry so far through leafless woods. In Missouri the bloom sits between mid-April and mid-May, just after the redbuds start and usually overlapping them. Kousa dogwood runs a month behind, flowering May into June with its bracts among fresh green leaves, weeks after the native tree has finished. Pacific dogwood flowers in spring and occasionally repeats in fall. Cornelian cherry works the other end of the calendar, opening tight clusters of small yellow flowers in early spring before its own leaves, and the southern selection 'Spring Glow' opens in late winter. A yard holding both therefore carries bloom from April into June.
Dogwood types and cultivars worth telling apart
Every pink or red flowering dogwood on the market traces back to a naturally occurring red-bracted variety of the otherwise white species. The crosses of flowering dogwood and kousa sell as one trade group under the Rutgers name, several cultivars of a single hybrid, and most resistance claims on nursery tags belong to those crosses or to kousa. Each claim covers one disease: spot anthracnose and dogwood anthracnose are not the same problem.
Which dogwood is which
Several trees are sold and photographed as dogwood. The bract tip, the bark and the fruit sort them fastest.
Where to plant a dogwood, and whether it suits your yard
A flowering dogwood earns its place in a yard that can give it high shade, acid soil that drains, and ground nobody mows; anywhere else it declines slowly. NC State calls it a tricky plant to grow in a yard setting and points urban gardeners toward other native trees: it asks more than most of the small flowering trees and shrubs people plant beside a front walk. Full sun to partial shade works in cooler country, while gardens in the piedmont and along the coast need more shade, especially in the afternoon. Leave room for air to move through the canopy, shelter the tree from wind, and keep it clear of road salt and traffic exhaust, both of which it takes badly.
Lawn is the wrong ground cover for a dogwood. Grass should not be grown over the root system, the tree loses the contest for moisture and does not live as long against turf, and the trunk needs protecting from mower and string trimmer injury. Poorly drained soil, wind, salt and drought stress all push a dogwood toward insect and disease problems. One thing works in its favor on an awkward site: flowering dogwood tolerates black walnut, so it can go under a tree that rules out most other planting.
The drawbacks are the ones no nursery tag lists. The tree flowers once and holds the rest of the year as a plain green understory tree, and it does not move well, so a specimen lost in its third year costs years to replace. On a site it dislikes, the failure is gradual: stress from poor cultural and environmental conditions, drought above all, opens a dogwood to disease and insect problems, and a trunk nicked by a mower is the opening a borer needs, which can kill a young tree in one to two seasons. Fruit drop is the other cost, worst on a kousa over paving, where the fallen fruit is enough of a mess to matter. Gardeners who want the look with less risk land on kousa, which carries better disease resistance and cold hardiness, is the standard substitute where dogwood anthracnose is a problem, and copes better with drought.
Height and spread
A flowering dogwood in a yard usually finishes between 15 and 30 feet tall and about as wide, with mature trees recorded to 20 to 40 feet. Site explains the gap: as an understory tree in woodland the species reaches 40 feet, while the same tree in the open may stop at 15 to 20 feet tall and wide, and spread often ends up greater than height. The habit is low-branching and broadly pyramidal with a somewhat flat top. Kousa covers similar ground at 15 to 30 feet, vase-shaped in its early years and rounding out with age, and the Rutgers hybrids stay smaller at 12 to 20 feet tall and 10 to 20 feet wide. Growth is unhurried, rated slow to medium: 15 feet in 18 years for a flowering dogwood, about 20 feet in 25 years for dogwoods generally, roughly 10 feet in 15 years for kousa. In the southern Appalachians height growth is fairly rapid for the first 20 to 30 years and then practically ceases.
Light
Morning sun with shade through the hot part of the afternoon is what a flowering dogwood wants. It is an understory species, classed as very tolerant of shade, and it does not tolerate long periods of full sun. Maximum photosynthesis happens at slightly less than one-third of full sunlight, so a dogwood is already working flat out in light that would starve most yard trees. Where leaf edges brown in summer heat or drought, the answer is more water, or shade over the hottest stretch of the afternoon. Light decides the shape as well: in shade the tree grows tall and thin with open horizontal branching, in sun shorter, denser and more compact. Kousa takes sun more easily, though its leaves can scorch in full sun if the soil dries out.
Water
Dogwoods want steady moisture and fail at both extremes, so water deeply through dry spells, 1 to 2 inches a week, especially where the tree stands in sun. The roots are shallow, and a shortage of water causes root dieback that shows up later as poor health and a shorter life; severe drought often kills mature trees outright, worst on dry sites and high ground, and on extremely dry sites the species cannot hold on at all. In southern forests dogwood leaves are the first to wilt in dry weather, and a long drought brings leaf fall and dieback of the tops. Mulch does most of the work of keeping the roots cool and moist: 2 to 4 inches of it, spread at least 8 to 10 feet across for a mature tree, carried to the canopy drip line where the feeder roots run, never piled against the trunk, which encourages rot. Run a sprinkler in the morning so the foliage dries early and leaf disease has less chance.
Soil and pH
Acid, organically rich soil that holds moisture and still drains is what a dogwood needs. Recommended ranges run from 5.5 to 6.0 up to 5.5 to 6.5, while wild trees turn up most often on soils of pH 6 to 7. Above that band the leaves go pale green with chlorosis, and heavy clay brings trouble of its own; on poorly drained clay the species is virtually absent in the wild, and seedling survival is low. That puts a dogwood in the same bed as azaleas and the rest of the acid-soil planting under high shade. Work compost or ground composted pine bark through the whole planting bed before the tree goes in.
USDA hardiness
Flowering dogwood is hardy through USDA zones 5 to 9, 5a through 9b in the finer split. Kousa stops a zone earlier at the warm end, 5 to 8, and cornelian cherry reaches a zone further north, 4 to 8. Pacific dogwood is hardy to zone 7 and a poor bet away from its own region: it often does badly in garden conditions, its bark is damaged by hot sun, and it is not suited to the eastern climate. Cold at the northern edge takes the flowers before it takes the tree. Flowering dogwood counts as borderline hardy around Chicago, and because it flowers on old wood, a harsh winter can damage the flower buds. Heat is the easier end: the tree is quite tolerant of it once established and carries a low flammability rating. One naturally occurring kousa variety, angustata, has stayed evergreen in upstate South Carolina down to 9 degrees Fahrenheit.
Planting
Fall is the best time to plant a dogwood. Buy container-grown where there is a choice, because containerized plants establish more quickly than field-grown balled and burlapped stock, and flowering dogwood does not transplant well to begin with. Nursery plants entering their third year are the ones suited to a permanent position. Do not lift a wild seedling from the woods: those plants often carry powdery mildew and spot anthracnose with them. A dogwood set too deep is an open invitation to the flatheaded appletree borer, which shows as cracked bark near the base of a young tree and dieback in the larger branches. Water is critical through the first year, because many young trees die in late summer for lack of moisture, before their roots have moved into the native soil.
Why a dogwood will not bloom
A dogwood that will not flower is almost always young, freshly moved, or standing in too much shade. Trees growing in sun produce more flowers than trees in shade, so a dogwood under a closed canopy can look healthy for years and still give you a handful of bracts. Age is the second answer: a seed-grown dogwood commonly flowers and fruits at six years old, some take seven to 10 years, and the starting age of seedlings varies, while almost every dogwood sold is asexually propagated and flowers early. Where early flowering matters, buy a grafted cultivar. The third answer catches people who did everything right. Missouri Botanical Garden records that balled and burlapped cultivars may bloom the first year and then not rebloom until their root systems are reestablished, which can take up to four years. That is the pattern behind the complaint of one full flowering after planting and then nothing, with no sign of damage anywhere on the tree. It is not sick in that case; it is spending everything it makes underground.
Weather and disease take the buds off an otherwise healthy tree. Failure to flower with damaged flower buds is a recognized dogwood problem, weather related or disease related, and dogwood anthracnose in particular reduces flowering and defoliates the tree in spring. Feeding works in both directions. A light spring feed once frost has passed, a balanced extended-release acid-forming azalea fertilizer with a second feed six weeks later, encourages extra flowers; heavy nitrogen pushes out succulent new shoots that infection moves into easily, and a tree already stressed by drought should not be fertilized through the summer.
Checks for a dogwood that will not flower
Most flowerless dogwoods are settled by the first two or three checks, all made from the ground. Work down in order, because the cheap fixes sit at the top and the ones that end in a chainsaw sit at the bottom.
Pruning and aftercare
Keep pruning to a minimum and do it after flowering, in early summer. Cornelian cherry follows the same rule, cut in spring once the yellow flowers have gone over. Dead wood is the exception worth acting on whenever it appears: taking dead branches back to living wood removes cankers that would otherwise spread into decay and further dieback, and selective cuts move air through the canopy. Cankered twigs and limbs come out during hot dry summer weather, and water sprouts are removed on sight. Where a tree stands over a patio or a walkway, shorten the low drooping branches. Every cut is also an opening. Dogwood borers become established only where they find a wound or a break in the bark, the adults are out from around mid-May through most of the summer, and the female is drawn to injured bark, scars and rough patches on the trunk.
Propagation and longevity
Flowering dogwood is propagated by seed or by stem cuttings. Seed carries an embryo dormancy that has to be broken first, so freshly collected seed is stratified at 41 degrees Fahrenheit for up to 120 days. Cuttings are quicker and more predictable: the species roots readily from wood taken in June or immediately after the plants bloom. The pink and red forms are the awkward ones, difficult from cuttings and usually budded in late summer or grafted in winter. Growers also use softwood cuttings in summer, hardwood cuttings in winter, grafting in winter or spring, suckers and divisions in spring, and budding in summer. Lifespan is given as up to 80 years under ideal conditions, and as 125 years for individual plants.
Pests and diseases
Dogwood trouble starts with a tree already under strain, and a stressed flowering dogwood is open to a long list of diseases, dogwood anthracnose among them. Discula destructiva, the fungus behind it, kills leaves, twigs and branches from the lower part of the tree upward, and a tree carrying its cankers usually dies within three to five years. Geography carries most of the risk: the disease is placed above 2,000 feet in South Carolina and at 1,800 feet or higher, with cases lower down where dogwoods sit in very cool, moist, shady spots. Once rated the worst disease of flowering dogwoods in yards and forests alike, it is recorded as less common now.
The diseases most gardeners actually meet are milder. Powdery mildew, from Erysiphe pulchra and Phyllactinia guttata, coats the leaves in white growth, dries them out and can strip a flowering dogwood of foliage; it settles into dense shaded sites with poor air circulation, and warm dry days followed by cool damp nights bring it on. In central Alabama it is the most severe and widespread dogwood disease. Spot anthracnose, the fungus Elsinoe corni, hits the flower bracts first, then leaves, young shoots and fruit; it is common and it is not severe. Two more arrive with wet springs: Septoria leaf spot, dark circular to angular spots about a quarter inch across with purple borders, and gray mold, tan spots ringed in pink on the fading bracts.
What kills a dogwood is usually at the trunk or under it. Crown canker, Phytophthora cactorum, is the most serious disease of flowering dogwoods in the eastern United States, and it gets in through wounds: transplanting damage, insects, animals, sunscald, lawn mowers, weed whips. A dogwood should never go back into the spot where a diseased one stood. On poorly drained ground, or where flooding is regular, root rot takes the tree from below. Winter sun on bare bark causes sunscald, usually on the southwest side of the trunk, and Botryosphaeria twig and branch canker runs more severely on the pink cultivars.
Among insects the one to know is the dogwood borer, the off-white, reddish-headed larva of a clearwing moth about 5/8 inch long at maturity; once it is inside the trunk control is difficult and the tree usually dies within a year or so, so the standard program is preventive, permethrin from early May, repeated four times at three-week intervals. The club-gall midge raises a spindle-shaped swelling half an inch to an inch long at a shoot tip, and the twig borer's feeding makes twigs die and break off. Kousa carries far less of this and is generally disease and pest free, and cornelian cherry is generally pest free too, with good resistance to powdery mildew and dogwood anthracnose in some tests.
What goes wrong most often
Ordered by how often each failure appears in a sample of seventy-three dogwood threads on Houzz, Garden.org, Ask Extension, ArboristSite and smaller forums, with questions about pruning and choosing a tree left out and Reddit not sampled.
Twelve threads, the largest group. Symptoms: limbs failing one at a time, a canopy thinning from below; in one central Alabama neighborhood ten or more large dogwoods worsened, died and fell within two to three years. Management: start at the roots and the drainage, since dieback traced to root rot, root damage or vascular trouble almost always ends in a slow death.
Eleven threads. Symptoms: a full canopy of healthy leaves and no bracts, often one strong spring right after planting and then nothing, or six years in the ground on a kousa with no flowers. Management: leave the root ball undisturbed and keep lawn feed off the root zone.
Ten threads. Symptoms: crisp brown margins, curling, leaves dropping early in a dry summer. Management: this is leaf scorch, and no plant pathogen causes it; mulch carried past the edge of the canopy and a deep soak are the answer.
Five threads. Symptoms: a white coating on upper and lower leaf surfaces, usually in spring only, followed by early purple and red leaf color. Management: powdery mildew, a common dogwood problem; thin whatever crowds the tree, and ask for a mildew-resistant selection next time.
Five threads. Symptoms: leaves that turn red and drop early, bark sloughing around holes in the trunk or branches, brown sawdust-like frass below the holes in late summer. Management: urgent, because infested young trees can be killed in one to two seasons.
Five threads, nearly all on red twig and other shrub dogwoods. Symptoms: larvae covered in a white powdery material after their second molt, yellowish with a shiny black head and black spots once mature. Management: gloves and hand removal usually settle it; Bacillus thuringiensis should not be used on them.
Telling the leaf problems apart
Four problems brown a dogwood leaf, and each leaves a different mark on the leaf and the twig.
Toxicity and pet safety
The red drupes on a flowering dogwood are bitter and inedible to people, poisonous by some accounts and flatly poisonous to humans by others. Kousa fruit sits at the other end of that line, technically edible and usually left to the birds. Dogwood has no entry at all on the ASPCA toxic and non-toxic plant list, which gathers the most frequently encountered plants reported to have systemic effects on animals or intense effects on the gastrointestinal tract and is described by its own authors as less than all-inclusive, so the absence settles nothing. For a dog that eats whatever falls, rake the drops out from under a flowering dogwood during fruiting and call a veterinarian if it swallows a quantity and then vomits or goes off its food.
Fall color, berries, and winter interest
Oval dark green leaves 3 to 6 inches long turn red in fall, red to reddish purple, in a good year a brilliant reddish purple over the whole canopy. Kousa holds its fall color for three to five weeks, and the color comes in stronger with more sun on the leaves. Fruit follows: glossy bright red oval drupes about half an inch long in tight clusters of three or four. Ripening moves with the region, July through August around Chicago and September into October in South Carolina, and clusters the birds overlook can hang until December. Kousa fruit matures pinkish red in summer and persists into fall.
The fruit is recorded as food for at least 36 species of birds, ruffed grouse, bobwhite quail and wild turkey among them, and chipmunks, foxes, black bear, skunks and squirrels take it as well. Insects use the tree too: it hosts the spring azure butterfly and raises the larvae of the dogwood thyatirid, the one-spotted variant, the friendly probole and the false crocus geometer. Even the fallen leaves work, breaking down faster than the litter of most other species so their minerals return to the soil sooner. Winter belongs to the bark on a kousa, mottled and exfoliating in tan and gray on mature trees.
Meaning and symbolism
In American use the dogwood stands for spring and rebirth, and the legend attached to it adds sacrifice and renewal. It also stands for a place: Missouri wrote it into law as the state tree in 1955. The symbolism comes out of one Ozark story. Old-time Ozarkers, as the folklorist Vance Randolph recorded them, held that the cross was made of dogwood, a tree said to have grown as tall as any large timber at the time, and that it was cursed for its part in the crucifixion to grow stunted and twisted, unfit for lumber. The legend reads the flower like a page: the cluster of true flowers at the center as a crown of thorns, and the shallow notches at the tips of the white bracts as nail holes with red or brown bloodstains. None of that is botany, and the Ozarks carried a competing tale that laid the same blame on the willow.
Forcing dogwood branches indoors
Dogwood can be cut in late winter and brought into bloom indoors, and cornelian cherry forces well too. Timing is most of the work: the closer the cutting date to the tree's normal flowering period, the less time the branches take to open. For scale, forsythia and pussywillow run one to three weeks indoors, apple and crabapple two to four, and magnolia three to five.
Dogwood beliefs that do not hold
Four things gardeners repeat about dogwoods that the plant records answer plainly.
The myth: Kousa is the same tree as the flowering dogwood, only later.
The reality: The two part company after bloom. Kousa fruit drops, ferments and draws yellow jackets, and seedlings come up prolifically underneath to the point of weediness.
The myth: Spotted bracts mean the tree is infected for life.
The reality: Bract spotting tracks the weather at bloom. When dry weather follows bud swell and flowering, the bracts may show few or no symptoms and that year's leaf infections are often less severe.
The myth: It is an understory tree, so it belongs in deep shade.
The reality: Full shade costs the second season: dogwoods sited there often color poorly in fall.
The myth: Deer leave dogwoods alone.
The reality: Foliage and twigs are browsed heavily by deer and rabbits, even though the tree is also listed as tolerating deer, so protect a young trunk. Kousa is rated mildly resistant to deer damage.
What to expect, year by year
A dogwood is bought for a spring show and judged on a schedule that has little to do with the first two springs.
Years one and two belong to the roots, and the tree above ground looks idle: little height, a thin canopy, and leaves that come off early in a dry August. This is also when a dogwood is most easily lost, so the work in those seasons is water and keeping metal away from the trunk.
From roughly the third season the tree settles into a rhythm: bracts every spring and a little more width each year. Early July is the date to mark, since the dogwood sawfly runs one generation each year and monitoring starts then.
Decades in, size and risk arrive together. Twenty year old Aurora specimens stand 20 feet high and wide, and Constellation about 20 feet high by 17 wide. Borers, drought stress and leaf scorch, sawfly and crown canker all rate as occasional problems over a mature tree's life.
Flower photos
FAQ
What month do dogwoods bloom?
April and May across most of the country, with the national spread running from mid-March in the South to late May in the North.
Why is my kousa dogwood not blooming?
Check the calendar first: kousa opens its bracts among the leaves in May and June, several weeks after the native dogwood has finished. 'Milky Way', a common selection, appears to flower biennially, so a heavy spring followed by a blank one can be normal.
How do you bring a dogwood back to life?
Start at the ground: check that the soil drains, pull back mulch piled against the trunk, and look for mower or trimmer damage at the base. Anthracnose gets the blame for most sick dogwoods, though it is rated not common and mainly a problem at 1,800 feet and higher, with the South Carolina threshold above 2,000 feet; where it takes hold it kills from the bottom of the tree upward, in three to five years.
Do coffee grounds help a dogwood bloom?
Shade, the age of the tree and a root system still reestablishing after planting account for most flowerless dogwoods, and none of the three is fixed by anything poured on the ground.
Which dogwood has the fewest disease problems?
Kousa is the usual answer, generally disease and pest free, with cornelian cherry close behind, generally pest free and resistant to powdery mildew and dogwood anthracnose in some tests. For the native tree, ask for a mildew-resistant selection such as 'Appalachian Joy', 'Cherokee Brave' or 'Weaver's White'.
Is there a dogwood that does not drop fruit?
'Plena' is the one to look for: semi-double white flowers, no fruit at all, and rated immune to spot anthracnose.
What is the smallest dogwood for a tight spot?
'Red Pygmy' is the true dwarf, 5 to 6 feet high and wide and small enough for a container. Where a narrow spot still wants a tree shape, the cornelian cherry 'Golden Glory' is upright at 12 to 15 feet high and 8 to 10 feet wide.
How far from the house should a dogwood be planted?
Measure for the crown. It can reach 15 to 30 feet across on a tree 15 to 25 feet high, and mature specimens are recorded at 40 feet tall and 35 feet wide.
What do dogwood flowers symbolize?
Spring and rebirth, with sacrifice and renewal carried by the old cross legend that Ozark storytellers attached to the tree.
Is red twig dogwood the same plant?
It is a shrub in the same genus, with its own weak point: red twig dogwood is rated highly susceptible to powdery mildew. The sawfly that strips shrub dogwoods in late summer somewhat prefers gray and yellow dogwood over the flowering tree.
What are the disadvantages of a dogwood tree?
Size first: it commonly finishes 15 to 30 feet across, wider than it is tall, so it needs more room than the trunk suggests. It is fussy about its site, and stress from poor conditions and drought opens it to disease and insects; a mower wound at the base lets in a borer that can kill a young tree in one to two seasons. Dropped fruit over paving is the last one, worst under a kousa.
Interesting tips
- Cornelian cherry is the dogwood you can pick fruit from. The southern selection 'Spring Glow' grows 20 feet tall and 15 feet wide and ripens red edible fruit in July.
- A yellow-fruited flowering dogwood exists. 'Xanthocarpa' carries the usual white bracts and then ripens yellow fruit.
- Nearly the whole dogwood harvest once went into shuttles for textile weaving, until plastic shuttles replaced that use.
Related Guides & Flowers
Magnolia
The other spring tree that opens its flowers before the leaves, on a frame that needs more room.
Azaleas
The acid-soil shrub that wants the same high shade and the same bed a dogwood needs.
Lilacs
The scented spring shrub for the open sunny ground where a dogwood struggles.
White flowers
More white-flowered plants to set beside the flat white bracts of a dogwood.