What a redbud is and where it comes from
Redbud is a small deciduous tree in the bean family, Fabaceae, native to eastern North America. Its natural range runs from New Jersey and southern Pennsylvania northwest to southern Michigan, southwest into southeastern Nebraska, south to central Texas and east to central Florida, with a separate population reaching from the Trans-Pecos and south Texas into Mexico. Despite the name canadensis the tree reaches Canada only on Pelee Island in Lake Erie and southern Ontario. Across that territory redbud is a regular but not a common understory component of many eastern forest types. Left alone it grows multi-trunked with a rounded crown, the trunk dividing close to the ground, while nursery cultivars are trained to a single stem.
The flowers are what people notice in March, and where they come from separates redbud from other spring trees: buds on old twigs, branches and the trunk itself. Bundles sit in the leaf axils and along the wood, most of them on two-year-old growth. Each flower is about half an inch wide with five petals and ten stamens, built like a pea blossom, and they open in clusters of 4 to 8, sometimes up to 10. Leaves arrive afterward: simple, alternate and heart-shaped, 3 to 5 inches long and wide with smooth entire margins, occasionally to 6 inches, bright green tinged red at first and dark green above, paler below, once expanded. The bark on an older trunk is dark red brown and scaly, splitting into deep fissures that show a cinnamon-orange interior.
Several other redbuds share the name. Two subspecies of Cercis canadensis are recognized: Texas redbud, var. texensis, in southern Oklahoma, Trans-Pecos Texas and southeastern New Mexico, and eastern redbud, var. canadensis, through the rest of the range. Oklahoma made the tree its state tree in 1937. California redbud, Cercis occidentalis, grows in Utah, Nevada, California and Arizona. The European species, Cercis siliquastrum, supplies the other common name: legend has Judas Iscariot hanging himself from a branch of it, so redbud is also called Judas-tree. Cercis itself comes from the Greek kerkis, a weaver's shuttle, after the shape of the seed pod.
When redbud blooms and how long the flowers last
Redbud flowers in early spring, ahead of its own leaves and ahead of most trees around it. Published bloom windows run March to May, with early May normal as far north as the Chicago region. Temperature does the scheduling: in Indiana the tree needs 30 days of temperatures averaging more than 50 degrees Fahrenheit before it opens. Once it starts, the display holds for about a month while most other trees are still bare, and individual flowers drop after 2 or 3 weeks as the leaves push out behind them.
The other kinds keep their own calendars. Chinese redbud blooms in very early spring for around 2 to 3 weeks, Texas redbud is showy from March to April before its foliage appears, and 'Forest Pansy' blooms later than the species, with darker, almost purple flowers. Age is less of a barrier than owners expect: redbuds have been recorded flowering at under 7 years old, though a tree does not set pods in that first flowering year, and some bloom profusely while still very small. The flowers are bisexual and the tree is self-pollinating, with bees usually doing the work.
Redbud varieties worth telling apart
Almost every named redbud sold here is a selection of the same species, picked for leaf color, mature size or a weeping habit. Leaf color is the part that unsettles buyers: 'Forest Pansy' opens reddish-purple, matures to a muted purple and turns more purplish-green in hot summers, which is normal for the cultivar in heat and no sign of a failing tree.
Which redbud is which
Four redbuds get mixed up with each other on nursery benches and in yards, and each one has a single tell that settles it.
Where to plant a redbud, and is it a good front yard tree
A redbud works as a front yard tree when the site suits it, and the site it wants is an edge: it prefers partial shade or edge habitats, and in a full sun or open field location it becomes vulnerable to summer drought. Native to the understory, it can still be grown in full to part sun, so the good spots in a suburban yard are the east side of the house, the gap between two larger trees, or the sunny margin of a wood line. The standard uses follow the same logic: a specimen in a pollinator garden, an understory tree in a wooded setting, a small group, or a mass planting for spring effect. Ground that stays wet rules a site out: redbud does not usually grow on flooded sites because it cannot endure inundation or survive in poorly aerated soils.
Distance from the house is set by the crown. Redbud finishes wider than it is tall, so the gap between the trunk and a wall, a walk or a driveway should be measured off half the mature spread. Branches also tend to break, which is why the tree should be sited in a relatively protected area: out of the wind funnel between two houses, and clear of the roofline where snow slides. Redbud can be planted as a street or lawn tree, though it is very sensitive to herbicides and chemicals sprayed on lawns, so the middle of a lawn on a weed-and-feed program is a slow way to lose one.
How big a redbud gets
Plan for 20 to 30 feet tall and 25 to 35 feet wide; a tighter 20 to 25 feet high and wide is also published. Below that spread sits a short trunk, or several trunks on a multistemmed tree, with spreading branches forming a broad, flat or rounded crown. Growth is quick while the tree is young and settles to medium afterward, so a redbud fills its width early and then appears to stall. Under optimum conditions a seedling can put on a foot of height in its first growing season.
Sun and shade
Redbud takes full sun, 6 or more hours of direct sunlight a day, or partial shade of 2 to 6 hours. Best flowering happens in full sun, so a tree planted for the spring display should get as much light as the site allows. In hot summer climates part shade is the better call. Shade has a floor, though. Old trees cannot normally tolerate severe competition and shade, so a redbud that started at the edge of a wood begins to fail as the canopy closes over it.
Watering a redbud
Keep a new redbud well watered until it is established, because it does not tolerate root disturbance and needs that time to settle. After that the guidance splits: an established tree tolerates drought but does better with regular watering, while heat and drought sit on the list of things it does not tolerate, alongside wet soils. In practice a redbud will get through a dry August and will grow better if it does not have to. In full sun, supplemental water during dry periods is part of the deal.
Soil and pH
Redbud is easily grown in average, medium moisture, well-drained soils, and it grows best where the ground stays moist but drains. pH is where the tree surprises people. It handles acid soil below 6.0, neutral soil from 6.0 to 8.0 and alkaline soil above 8.0, and it grows best where the pH is above 7.5, being prevalent on limestone outcrops and alkaline soils. A chalky, limey yard that frustrates acid-loving shrubs is reasonable ground for a redbud. In the wild the species turns up on sites from xeric to mesic and is most abundant on south-facing slopes. It also tolerates juglone well enough to be grown under a black walnut.
Cold hardiness and where redbud grows
Eastern redbud is hardy through USDA zones 4a to 9b, though published ranges also stop at zone 8. Hardiness varies considerably between individual redbuds: trees raised from more southern seed may lack sufficient cold hardiness, so in zone 5a and colder buy from a local or regional source. Twig kill and dieback in colder zones is common, worth remembering before a northern owner starts hunting for a disease. Cold-hardy seed strains exist for exactly this, among them 'Columbus' out of Wisconsin and 'Northland Strain' and MN Strain out of Minnesota.
At the warm and dry end the choice shifts to other kinds of redbud. Texas redbud, var. texensis, is winter hardy to zone 6 where the species goes to zone 4. Western redbud tolerates cold to 15 to 20 degrees Fahrenheit and grows easily almost anywhere in northern California that stays above 15 degrees. In southern California it wants seasonal streams, springs, damp areas or irrigated ground and a cool winter, which the immediate coast does not give it. None of the Texas, Mexican or western kinds are hardy in the Midwest. 'Forest Pansy' carries a zone 5 to 9 rating, and information on its hardiness is conflicting.
Planting: when, what size, and why it hates being moved
Plant a redbud in spring, in part shade, and plant it young. The tree does not transplant well because it develops a deep taproot, so young stock establishes best, and once it is in the ground it should be left undisturbed. That taproot descends rapidly in the first few years if the soil permits, and where an impenetrable subsoil blocks it, the taproot turns and grows horizontally. Put it in its permanent position as soon as possible: buy the smallest tree you are willing to wait for, and give up in advance on moving it the year the deck goes in. A 3 to 4 inch layer of organic mulch protects the shallow root system, and a mulch ring wide enough to keep a mower and a string trimmer away from the bark earns its place. Regular watering, fertilization and pruning out dead branches as needed keep the tree vigorous after that.
Pruning young, and pruning around disease
A redbud needs pruning while it is young to develop a good shape and strong structure. The reason sits in the wood: it can be brittle, with potential for splitting at crotches and branches breaking off in wind and heavy snow, and the multi-stemmed habit that makes the tree handsome also builds the tight crotches that fail first. The work after planting is choosing the permanent scaffold, taking out one of any pair of stems that press against each other, and making those cuts while they are still small, since cankers are often centered at branch stubs and other wounds where the fungus gains entry.
Avoid pruning during wet periods in spring, when the canker fungus is most actively sporulating, and sanitize pruning tools after working on any plant known or suspected to be infected; prune in dry weather. When you are cutting out a canker, cut well past it, at least 6 to 12 inches away from the blighted tissue, and take the diseased wood off the site. Disinfect tools between cuts by dipping them in alcohol or a 10 percent bleach solution. No cut cures a limb that is already gone, because individual cankers are produced in such numbers that they coalesce and girdle shoots and branches.
Growing new redbuds, and how long one lives
The species comes easily from seed, while cultivars have to be budded onto seedling rootstock or grown from summer cuttings. Seed takes work: scarification or immersion in boiling water or concentrated sulfuric acid for about 30 minutes, then stratification in moist sand at about 41 degrees Fahrenheit for 5 to 8 weeks, and western redbud wants the same, hot water and two months of stratification. Seed that simply drops usually stays dormant for several years, which is why volunteers appear in a bed long after a heavy pod year. Under ideal conditions a redbud self-seeds, though usually not to the point of being problematic, and many trees are sterile and produce no fruit at all. Lifespan is unsettled. The Morton Arboretum gives redbud a 20 to 25 year life span, while NC State Extension records it as short-lived at typically less than 75 years. The tree tends to be short-lived especially if stressed. Old redbuds usually suffer from heart rot, which is how a tree that looked settled for years starts shedding limbs.
What kills a redbud, and what can be done
Three diseases carry the tree's reputation, leaf anthracnose, Botryosphaeria canker and verticillium wilt, and the most serious of them is the canker Botryosphaeria ribis and its variety chromogena. That parasitic variety produces stem and twig lesions, and entire groves of redbuds have been killed by it. How the fungus lives explains a settled-looking tree going downhill in one season: these are opportunistic pathogens that attack weakened and stressed hosts, and some sit inside the plant as endophytes, causing no symptoms until it becomes stressed. It is an organism waiting for a bad year rather than one that breaks into sound wood. No effective chemical control is available.
Verticillium wilt is the other killer, and it sometimes kills redbuds outright, especially in the Midwest. No Cercis escapes it: every species tested is susceptible, eastern, Chinese and western redbud and the European Judas tree among them. Wet sites raise the odds. Once the fungus has the tree the progression is blunt: branch dieback follows, entire branches are killed, and in a severe infection the whole tree wilts and dies suddenly.
A newer trouble sits behind some of the dieback that gets called wilt. Vascular streak dieback is the gradual but progressive death of individual branches from the tips toward the main stem, and streaking shows inside the water-conducting xylem of infected branches. The fungus Ceratobasidium theobromae has been consistently associated with the vascular tissue of nursery stock carrying those symptoms, though no one has completed Koch's postulates with the fungus isolated from symptomatic redbud, so the cause is still unconfirmed. Insects are the smaller half of the story: redbud has few insect pests other than scales, and damage from the insects it does host is not normally severe. What turns up runs to Japanese beetles, treehoppers, leafhoppers, caterpillars, borers, webworms and scale, along with leaf spots, mildew and blights, and the redbud leaffolder, Fascista cercerisella, feeds on leaves that its larvae web together.
What owners actually run into
Ordered as they came up in a sample of eighty-seven homeowner threads on garden forums and extension question lines. The sample is not random: two sites supply most of it, and Reddit is under-represented.
Twenty-five threads, the largest group by a wide margin. The tree comes through spring with part of the crown bare, and the first question is almost always whether it can be saved.
Owners of lopsided, bifurcated or overgrown trees want to know how much wood they can take at once and in what month. Ten threads.
Nine threads, with owners trying to tell heat stress from something moving in the wood.
Pods hang through the cold months and weigh branches down, and seedlings come up in beds and lawns where they get pulled as weeds. Eight threads.
Eight threads, most about purple-leaved trees whose color goes green or bronze by midsummer, and whether that means a sick tree or a misled buyer.
A spring-planted tree drops its leaves or leafs out weeks after everything else, and the owner reads it as death. Six threads.
Four threads.
Holes in the trunk, and rows of egg masses stuck along the bark that owners photograph and cannot name. Three threads.
Why a redbud is dying, in order
Work the checks in order. What has happened to the tree and what it is standing in come first, because both can still be changed; the naming of a disease comes after that.
The case for and against planting one
The case for a redbud is early bloom on a small tree that asks for very little; the case against is a short life and a habit of getting sick once something else has weakened it. It is genuinely tolerant of shade, and once established it endures a good deal of shading, which puts a flowering tree at the edge of a canopy, where most flowering trees sulk. It is particularly resistant to black walnut and clay soils and to compaction, so the scraped, driven-over ground around a newer house does not disqualify a site. Deer tend to avoid it. Insect problems are minor enough that they should not discourage planting one, and for a tree this size the wildlife load is heavy: 12 species of Lepidoptera use redbud as a larval host.
Against that sits the one problem recorded for the species, on a tree whose maintenance is otherwise low: redbud is small and short-lived. The diseases that kill redbuds work on trees already weakened, so a drought year, a mower wound or a wet corner is what turns a healthy tree into a declining one, and the cost shows up as limbs to cut, season after season. Messy fruit and plant parts come with it, which in a yard means pods to rake in winter and seedlings to pull out of beds in spring.
Toxicity, pets, and the edible flowers
Redbud does not appear on the ASPCA lists of toxic and non-toxic plants in either direction, and those lists cover the most frequently encountered plants and are not all-inclusive, so the silence settles nothing on its own. The general caution applies: eating any plant material may cause vomiting and gastrointestinal upset in dogs and cats. For people the record points the other way and is specific to the flowers, which are edible, taste similar to peas and contain high amounts of vitamin C. They are used in salads or fried.
Leaves, fall color, and the seed pods
Leaves may turn a bright, clear yellow in some years, but good fall color is unreliable, and pale yellow to greenish-yellow is the more usual result. Selections bred for foliage change that arithmetic: 'Forest Pansy' colors variably in fall, often in shades of reddish-purple and orange, Golden Falls carries golden yellow leaves on a weeping frame, and 'Vanilla Twist' opens chartreuse, matures to light green and finishes yellow, with pure white flowers on a weeping habit. Pods are the part people complain about. Flattened and bean-like, 2 to 4 inches long, they mature brown in summer, hold 6 to 12 seeds each and can stay on the tree into winter. Brown pods hanging through the cold months look untidy, and whether they persist or fall in early winter varies.
What a redbud feeds
The flowers open when little else does, which is where most of the tree's wildlife value sits. Many pollinators visit them, though only long-tongued bees can reach the nectaries, and the flowers are regarded as important in the production of honey. Those early blossoms also draw nectar-seeking insects including several species of early-season butterflies, while hummingbirds take the nectar and songbirds eat the seeds and the flower buds. Its caterpillars appear from February to May in a single flight, and the adult Henry's Elfin butterflies feed on flower nectar. Cardinals, ring-necked pheasants, rose-breasted grosbeaks, bobwhites, white-tailed deer and gray squirrels have all been recorded feeding on redbud seeds.
Forcing redbud branches indoors
Redbud is a good cut flower for forcing indoors and one of the few trees and shrubs suited to it. Forcing can start as soon as buds swell in late winter, though March is the month for the harder-to-force ornamentals, crabapples, magnolias and redbuds among them. Time to open varies by species, from forsythia at one to three weeks to magnolia at three to five, and the closer the date is to the tree's normal flowering outdoors, the less time forcing takes.
Four things people get wrong about redbuds
Each of these changes what an owner does next.
The myth: Dead branches on a redbud mean verticillium wilt.
The reality: Several causes produce the same picture. Wilt is confused with vascular streak dieback and has been misdiagnosed in the past, so the diagnosis comes from the wood and the pattern of dieback.
The myth: A fungicide will cure a wilted redbud.
The reality: Fungicides are not effective at curing infected trees. The work left is sanitation, removal of affected wood, and taking the stress off whatever crown remains.
The myth: 'Forest Pansy' is a different tree from the native redbud.
The reality: It is a purple-leaved cultivar of the same native redbud species, sold under its own name because of the foliage.
The myth: Redbud flowers are red.
The reality: What opens runs from light rosy pink to dark magenta, and white forms exist, which puts redbud among the pink spring flowers, with 'Alba' blooming a little later than the species.
What to expect from a redbud over time
A redbud runs on a shorter clock than the shade trees around it.
Years one to three go into the roots and into what you bought. Vascular streak dieback has moved through nursery stock hard enough that in some cases 90 to 100 percent of it was unsellable, so the leader and the current season's growth deserve a close look before a tree leaves the lot. The structural pruning that decides the shape of the tree belongs in these years.
The middle years are what the tree was bought for: bloom on bare wood every spring, a crown filled out to something near its mature width, and pods in the years the crop sets. Fruiting is erratic, since heavy crops do not come every year, and when the pods are numerous they can detract from the look of the tree.
An infected tree may die within a few weeks or live for years with symptoms coming back season after season, and a declining redbud pushes water sprouts below its dead branches.
Flower photos
FAQ
How big does a redbud tree get?
Plan for a crown 25 to 35 feet across on a tree 20 to 30 feet tall.
Is a redbud a good front yard tree?
Yes on an edge position with ground that drains, since a tree left in open full sun becomes vulnerable to summer drought.
How many years before a redbud flowers?
Earlier than most buyers expect, and the first flowering year passes without pods.
Why is my redbud not blooming?
Light is the first thing to check, because the best flowering happens in full sun. In colder zones twig kill and dieback are common, and the flowers form mostly on two-year-old wood, so the twigs a hard winter takes carry next spring's bloom away with them.
How do I tell verticillium wilt from canker on a redbud?
Wilt shows inside the wood, as dark brown to orangish streaks in the sapwood of a dying limb; canker shows on the outside, as sunken lesions and bark that cracks, splits or sloughs.
Can a dying redbud be saved?
Fungicides are not effective on a tree that is already infected, so what is left is cutting the affected wood out and taking the stress off the roots.
How long do redbud trees live?
Published figures disagree by decades, at 20 to 25 years and at typically less than 75 years.
Is there a dwarf redbud for a small yard?
'Ace of Hearts' is the dwarf, given both as 10 to 12 feet tall and as 12 to 15 feet high and wide.
What is the difference between Texas or 'Oklahoma' redbud and the eastern kind?
Texas redbud is smaller and more drought tolerant than its eastern relative and wants thin, calcareous, well-drained soil that is not acidic, and it is rated for zones 6a through 9b. Published sizes put it at 20 to 30 feet tall and 15 to 25 feet wide, and a second published figure gives 25 to 30 feet tall. 'Oklahoma' is a more compact, broad-rounded form of that same Texas variety.
Are redbuds toxic to dogs and cats?
Redbud appears on the standard pet plant lists in neither direction, and absence from a list that covers only the most frequently encountered plants is not a clearance.
Interesting tips
- Most decay fungi get into a tree through wounds on stressed wood, and the common one in a yard is the string trimmer at the base of the trunk.
- The pod cleanup can be designed out at the nursery: 'Don Egolf', the single-trunk Chinese redbud, is sterile and sets no seed pods.
- Doubled flowers exist in the genus: 'Pink Pom Poms' carries double pink flowers.
Related Guides & Flowers
Magnolia
The other spring tree that opens its flowers before the leaves, on a much bigger scale.
Forsythia
The yellow shrub that flowers on bare stems in the same early weeks of spring.
Lilacs
The scented shrub that carries the garden on once the early flowering trees have dropped their petals.
Purple flowers
A run through purple garden flowers for anyone drawn to the darker end of the redbud range.