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American Hornbeam - Carpinus caroliniana |
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| Common Name: |
American Hornbeam (also called Blue-Beech, Ironwood) |
| Scientific Name: |
Carpinus caroliniana |
| Hardiness Zone: |
3A through 9A |
| Family: |
Betulaceae |
General Information
Was first discovered and named in North Carolina. Can be found in the eastern USA. A handsome tree in many locations, the tree slowly reaches a height and spread of 20 to 30 feet. It will grow with an attractive open habit in total shade, but be dense in full sun. The muscle-like bark is smooth, gray and fluted. Ironwood has a slow growth rate and is reportedly difficult to transplant from a field nursery (although 10-inch-diameter trees were moved with a 90-inch tree spade during the winter in USDA hardiness zone 8b with no problem) but is easy from containers. The fall color is faintly orange to yellow and stands out in the landscape or woods in the fall. Brown leaves occasionally hang on the tree into the winter.
Basic Care
| Bark Characteristics: |
Bark Characteristic: smooth grey bark musle like bark. |
| Leaf/Foliage Characteristics: |
Leaf arrangement: alternate. Leaf margin: double serrate. Leaf shape: ovate, oblong. Leaf blade length: 2 to 4 inches Leaf color: green. Fall color: red, yellow, orange. |
| Growth Characteristics |
Height: 20 to 30 feet. Spread: 20 to 30 feet. Growth rate: slow. |
| Flower/Fruit Characteristics: |
Flower color: orange/yellow. Flower characteristics: not showy. Fruit shape: elongated, oval. Fruit length: .5 to 1 inch. Fruit color: brown |
| Lighting: |
full sun, partial sun or partial shade, shade tolerant. |
| Watering: |
Moderate, increasing in summer. Never let the soil dry completely. |
| Feeding: |
Feed Every 20-30 days starting after bud break. Ordinary plant food at half strength or use organic which will feed with each watering. |
| Pruning/Wiring: |
Can be wired from spring to autumn - some bark protection may be needed, but the hornbeam is fairly sturdy for a deciduous tree. Accepts repeated pruning, quickly healing scars. Prune back to the first pair of leaves on new shoots. Select the cutting point on the branch so that the new growth grows in the direction planned. In early spring remove buds or young branches that are growing upwards or downwards. Allow several leaves to develop, then cut back to one or two leaves on each new branch. The best times for minor pruning are early spring and after flowering. Major developmental pruning should be done in late winter, before bud burst. Strong apical growth of upper part of tree, so it may be necessary to cut back radically at the apex, but to prune the lower portions of the tree conservatively, especially with the Japanese species, to check its rapid apical growth. As the tree ages, branches may die back for no discernable reason. |
| Propagation: |
Seed, air-layering, cuttings. |
| Potting: |
Every 2-3 years in early spring before buds break. Use a soil mix that allows good drainage. Prefers a deep pot. |
| Pests: |
Relatively few insects attack hornbeam. Maple phenacoccus forms white cottony masses on the undersides of the leaves. |
| Diseases: |
None are normally very serious. Several fungi cause leaf spots on Carpinus. Leaf spots are not serious so control measures are usually not needed. Canker, caused by several fungi, causes infected branches to dieback and entire trees die if the trunk is infected and girdled. Severely infected trees can not be saved and infected branches are pruned out. This could limit usefulness in parts of the Deep South. |
| Bibliography: |
edis.ifas.ufl.edu/ST118 |
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