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Part of the elm (Ulmaceae) family, Hackberry can reach more than sixty feet tall in the landscape, with leaves up to
five inches long. The internodes and leaf sizes can be reduced drastically however through bonsai techniques, and
they can make very handsome specimens. Shiny, oval, blunt-toothed leaves in medium green, they have nearly
insignificant white or green flowers in the spring. Though difficult to get depending on growing conditions,
hackberry fruit is tiny (about a 1/4 inch in diameter), ranging in colour from orange to red to purple, and well
suited for bonsai sized trees. Hackberry are deciduous, and require a period of dormancy, though they are
commonly sold as indoor bonsai. Keep them indoors if you can provide the light necessary, as well as a period of
dormancy during the winter. Otherwise keep these outside.
Hardiness: Zone 5 in landscape. Need winter protection. Can tolerate freezing for up to a week at a time, but keep
in an unheated garage or shed during stretches of intense cold. Enjoy and tolerate very hot summers if kept moist
enough.
Light: Full sun. Tolerates partial shade, but will not grow as vigorously. Shade pots (but not foliage) during the
hottest parts of the day.
Soil: Prefers richer soil, but tolerates most standard soil mixes.
Watering: Water well in growing season. Will wilt and shed leaves quickly due to dry roots. Do not allow to dry
out during dormancy, though they do require less water.
Fertilizer: Well balanced fertilizer every week for the month following budbreak, down to once every two weeks
through spring and summer. Nitrogen free from late summer until leaf fall. None in winter.
Pests and Diseases: Spider mites and scale. Leaf spot. Not susceptible to Dutch Elm disease.
Repotting: Every year to three years, depending on the age of the tree. Hackberry tend to do better in slightly
deeper pots.
Pruning and Styling: Growth can be very rapid during the heat of summer, provided enough water and humidity.
Allow to grow out to eight or ten leaves, pruning to one or two leaves. New twigs will sprout from cut branches
and shoots at the location of the pruning, as well as further back along the branches. Pruning can cause several new
shoots to sprout from the same location. Reduce new growth to two new shoots if this occurs. This will form a
dense canopy, but will lessen the amount of flowers and fruit. Hackberry will suffer from dieback on interior
branches if the canopy becomes too dense, so be sure to clear out unwanted branches and thin as needed to allow
light and airflow into the inner parts of the tree. Heavy pruning and thinning can be done well in late winter or
early spring, as the branch structure is easy to see when the tree is not in leaf.
Propagation: Airlayering in spring. Softwood cuttings in lat spring to midsummer. Sow seeds outside in autumn.
Styles and Forms: Suited to most styles.
Species and Cultivars: C. sinensis - Chinese hackberry. Bright orange fruit. Hardy to zone 7.
C. occidentalis - Native to North America. Red to yellow fruit. Hardy to zone 3.
Other Information:
five inches long. The internodes and leaf sizes can be reduced drastically however through bonsai techniques, and
they can make very handsome specimens. Shiny, oval, blunt-toothed leaves in medium green, they have nearly
insignificant white or green flowers in the spring. Though difficult to get depending on growing conditions,
hackberry fruit is tiny (about a 1/4 inch in diameter), ranging in colour from orange to red to purple, and well
suited for bonsai sized trees. Hackberry are deciduous, and require a period of dormancy, though they are
commonly sold as indoor bonsai. Keep them indoors if you can provide the light necessary, as well as a period of
dormancy during the winter. Otherwise keep these outside.
Hardiness: Zone 5 in landscape. Need winter protection. Can tolerate freezing for up to a week at a time, but keep
in an unheated garage or shed during stretches of intense cold. Enjoy and tolerate very hot summers if kept moist
enough.
Light: Full sun. Tolerates partial shade, but will not grow as vigorously. Shade pots (but not foliage) during the
hottest parts of the day.
Soil: Prefers richer soil, but tolerates most standard soil mixes.
Watering: Water well in growing season. Will wilt and shed leaves quickly due to dry roots. Do not allow to dry
out during dormancy, though they do require less water.
Fertilizer: Well balanced fertilizer every week for the month following budbreak, down to once every two weeks
through spring and summer. Nitrogen free from late summer until leaf fall. None in winter.
Pests and Diseases: Spider mites and scale. Leaf spot. Not susceptible to Dutch Elm disease.
Repotting: Every year to three years, depending on the age of the tree. Hackberry tend to do better in slightly
deeper pots.
Pruning and Styling: Growth can be very rapid during the heat of summer, provided enough water and humidity.
Allow to grow out to eight or ten leaves, pruning to one or two leaves. New twigs will sprout from cut branches
and shoots at the location of the pruning, as well as further back along the branches. Pruning can cause several new
shoots to sprout from the same location. Reduce new growth to two new shoots if this occurs. This will form a
dense canopy, but will lessen the amount of flowers and fruit. Hackberry will suffer from dieback on interior
branches if the canopy becomes too dense, so be sure to clear out unwanted branches and thin as needed to allow
light and airflow into the inner parts of the tree. Heavy pruning and thinning can be done well in late winter or
early spring, as the branch structure is easy to see when the tree is not in leaf.
Propagation: Airlayering in spring. Softwood cuttings in lat spring to midsummer. Sow seeds outside in autumn.
Styles and Forms: Suited to most styles.
Species and Cultivars: C. sinensis - Chinese hackberry. Bright orange fruit. Hardy to zone 7.
C. occidentalis - Native to North America. Red to yellow fruit. Hardy to zone 3.
Other Information:
Hackberry (Celtis)