Introduction
The state tree of Oklahoma, Eastern Redbud is a moderate to rapid-grower when young, reaching a height of 20 to 30 feet. `Flame' Eastern Redbud shows double pink flowers all over the tree in spring, just before the leaves emerge. Thirty-year-old specimens are rare but they probably can reach 35 feet in height forming a rounded vase. The pink flowers are displayed later than the species and are sterile so there is no fruit set. `Flame' Eastern Redbud has an irregular growth habit and is more upright than the species when young but forms a graceful flat-topped vase-shape or globe as it gets older. The tree usually branches low on the trunk, and if left intact forms a graceful multitrunked habit. Be sure to avoid weak forks by pruning to reduce the size of lateral branches and save those which form a `U'-shaped crotch, not a `V'. Keep them less than half the diameter of the main trunk to increase longevity of the tree. Do not allow multiple trunks to grow with tight crotches, instead space branches about 6 to 10 inches apart along a main trunk. Yellow (although somewhat variable and unreliable) fall color and tolerance to partial shade make this a suitable, attractive tree for understory or specimen planting. Best not used as a street tree due to low disease resistance and short life, but is nice in commercial and residential landscapes. Plant in a shrub border for a spring and fall color display.
General Information
Scientific name: Cercis canadensis
Pronunciation: SER-sis kan-uh-DEN-sis
Common name(s): 'Flame' Eastern Redbud
Family: Leguminosae
USDA hardiness zones: 4B through 9A (Fig. 2)
Origin: native to North America
Invasive potential: little invasive potential
Uses: container or planter; tree lawn 3-4 feet wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; street without sidewalk; sidewalk cutout (tree pit); parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; deck or patio; shade; specimen; reclamation; highway median
Availability: not native to North America
Description
Height: 20 to 30 feet
Spread: 15 to 25 feet
Crown uniformity: irregular
Crown shape: vase, round
Crown density: moderate
Growth rate: fast
Texture: coarse
Foliage
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: entire
Leaf shape: ovate, orbiculate
Leaf venation: palmate, reticulate, brachidodrome, pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches, 4 to 8 inches
Leaf color: green
Fall color: yellow
Fall characteristic: showy
Flower
Flower color: pink, lavender, purple
Flower characteristics: very showy
Fruit
Fruit shape: no fruit
Fruit length: no fruit
Fruit covering: no fruit
Fruit color: no fruit
Fruit characteristics: no fruit
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns
Pruning requirement: needed for strong structure
Breakage: susceptible to breakage
Current year twig color: brown
Current year twig thickness: medium
Wood specific gravity: unknown
Culture
Light requirement: full sun, partial sun or partial shade
Soil tolerances: sand; loam; clay; acidic; alkaline; occasionally wet; well-drained
Drought tolerance: high
Aerosol salt tolerance: none
Other
Roots: not a problem
Winter interest: no
Outstanding tree: no
Ozone sensitivity: unknown
Verticillium wilt susceptibility: susceptible
Pest resistance: low resistance to pests/diseases
Use and Management
Eastern Redbuds grow well in full sun in the northern part of its range but will benefit from some shade in the southern zones, particularly in the lower mid-west where summers are hot. Best growth occurs in a light, rich, moist soil but adapts well to a variety of soil including sandy or alkaline. Trees look better when they receive some irrigation in summer dry spells. Its native habitat ranges from stream bank to dry ridge, demonstrating its adaptability. Trees are sold as single or multistemmed. Young trees are easiest to transplant and survive best when planted in the spring or fall. Containerized trees can be planted anytime. The beans provide food for some birds. Trees are short-lived but provide a wonderful show in the spring and fall.
Several other cultivars of Eastern Redbud may be seen: `Pink Charm' - flowers pink; `Pinkbud' - flowers pink; `Purple Leaf' - young foliage purple; `Forest Pansy' is a particularly attractive cultivar with purple-red leaves in the spring, but color fades to green in the summer in the south. Cercis canadensis var. texensis `Texas White' and Cercis reniformis `Oklahoma' have far superior foliage and make wonderful substitutes for the Eastern Redbud, particularly in non-irrigated areas. These are also better for central and western Oklahoma and Texas.
Cercis cultivars can be propagated by grafting onto seedlings, or by summer cuttings under mist or in a greenhouse.
Pests
Borers attack the trunk of older and stressed trees. Keep the plant vigorous.
Scale insects can usually be controlled with horticultural sprays.
Webworm can defoliate parts of the tree in summer and fall.
Diseases
Canker is the biggest problem with Eastern Redbud. Dieback begins as a canker on a branch. The cankers, at first small and sunken, enlarge to girdle the branch. Bark in the canker turns black and a crack forms between diseased and healthy bark. The fungus enters through wounds or dead and dying branches. Once girdled, the part of the stem beyond the canker wilts and dies. There is no chemical control. Prune out diseased branches.
Leaf spots can be a problem during wet weather. Since the disease is rarely serious, no chemical controls are suggested.
Verticillium wilt attacks and kills Eastern Redbud. Fertilize affected trees with nitrogen fertilizer and prune out wilted branches.
