Celtis

( SELL - tiss )

At-A-Glance Information

Commonly referred to as Hackberry or Nettle Tree, this genus of deciduous trees requires full sun to partial shade and moderate water. The fruits produced by these shade trees will attract birds to your garden. Mature trees have cork-like bark and deep roots, and foliage turns yellow in cooler fall temperatures. These trees can tolerate strong winds and being planted near roads and walkways (where they don't cause damage to hardscaped areas). Hackberry can also tolerate desert heat, alkaline soils, and drought and do not need much  pruning to take on a handsome shape. Use these low-maintenance trees as street or shade trees or as specimens in the landscape.

celtis Species and Varietals

The genus Celtis is a member of the plant family Cannabaceae and includes between 60 and 70 species. Hackberry growing zones vary depending on the species; for more information consult the descriptions below. To find your zone, click here: Zone Map.

Celtis australis (European Nettle Tree, Mediterranean Hackberry, Lote Tree, Honeyberry)
This species is native to southern Europe, Asia Minor, and north Africa and reaches between 33 and 82 feet tall when mature. Foliage is green, flowers are white to cream-colored, and fruits are green and mature to black.

Celtis caucasica (Caucasian Hackberry, Caucasian Nettle Tree)
Native to the Caucasus, Central Asia, and the western Himalayan region, these trees are commonly grown as street trees. Their roots are non-invasive, making them perfect candidates for installation near paved areas. 

Celtis julianae (Julian Hackberry)
Native to southern and central areas of China, these trees are fast-growing and have greyish bark. Typically, these trees will reach about 80 feet tall. These trees are used as street trees in many cities in China and France. 

Celtis koraiensis (Korean Hackberry)
This species is endemic to the Korean Peninsula and northern China. These trees produce cream to white flowers in April to May, followed by fruits that ripen in September and October. Korean Hackberry reaches about 50 feet tall when mature.

Celtis laevigata (Sugarberry, Sugar Hackberry, Southern Hackberry)
​These trees are native to the eastern United States over through Texas and northeastern Mexico, where it primarily grows along streambeds and in moist areas. These are attractive landscaping trees that serve as fantastic shade trees and produce sweet berries.

Celtis occidentalis (Common Hackberry, Sugarberry, Beaverwood, Northern Hackberry, American Hackberry)
This species is best in zones 1-24 and is native to eastern North America. These trees reach 50 feet or taller and have bright green leaves. Common Hackberry has a rounded, somewhat pendulous habit, and does not leaf out until the middle of springtime. This species is resistant to Oak Root Fungus. Variety 'Magnifica' (actually a hybrid between C. laevigata and C. occidentalis) is a great garden variety with dark green leaves and insect pest resistance.

​Celtis pallida (Celtis ehrenbergiana) (Desert Hackberry, Granjeno, Spiny Hackberry)
Best in zones 10-13, this species is native to the southwestern United States and northern Mexico. It forms a small shrub or tree with dense foliage and spiny growth, reaching 18 feet tall. Berries are orange and small. Useful desert planting for encouraging biodiversity, as a screen or barrier, and for erosion control.

Celtis paniculata (Tripewood, Silky Keltis, Silky Celtis, Native Hackberry, Native Celtis, Investigator Tree, Whitewood)
This rainforest-dwelling species is native to Malesia, Melanesia, and Australia. Trees can reach 130 feet tall when mature, and have greyish-brown thin bark. Flowers are green, blooming in December and January, and fruits ripen the following July through March in the tree's native range. 

​Celtis reticulata (Celtis douglasii) (Western Hackberry, Netleaf Hackberry, Acibuche, Palo Blanco, Douglas Hackberry, Netleaf Sugar Hackberry)
This species grows well in zones 2-24 and is native to Idaho, eastern Washington, northern Oregon through Utah, and mountainous areas from Arizona through Southern California. These trees reach 25-30 feet tall and wide, and have pendulous branches and toothed leaves that are whitish underneath.

​Celtis sinensis (Chinese Hackberry, Yunnan Hackberry, Japanese Hackberry)
This species is native to East Asia and does best in zones 8-16 and 18-20. It is similar to Celtis occidentalis, but only reaches 40-60 feet tall and about as wide. Leaves are smooth and glossy, and have scalloped edges. These trees are commonly used in traditional eastern Asian landscapes as ornamental shade trees. 'Green Cascade' is a beautiful, weeping form of this species.

Celtis tenuifolia (Dwarf Hackberry, Georgia Hackberry)
These trees are native to eastern areas of North America, and are considered threatened with extinction in Canada. These trees are tolerant of drought but not shade, and grow in many different habitats. These trees are great for increasing biodiversity in the landscape, as their berries are bird favorites.

Celtis tetranda (Nilgiri Elm)
These trees have a wide native range, including the Indian Subcontinent, southern China, Southeast Asia, and western areas of Indonesia. These trees are occasionally available for purchase through nurseries or commercial growers.

Caring for and pruning celtis Trees

Choose a planting spot in the landscape that is in full sun; these trees can tolerate partial shade as well. Hackberry should get at least 6 hours of direct sun each day. These trees are adaptable to a wide range of soils, including clay, sand, and loam. As long as soil is well-draining, these trees can tolerate even poor soil conditions that is compacted and infertile. After planting, apply a layer of mulch around the base of the tree to help increase soil moisture retention and suppress weed growth. Newly planted trees should be watered regularly during the first two years after installation. Once established, Hackberry trees are considered to be drought-tolerant, simply needing infrequent deep waterings during prolonged dry weather. These trees do not require fertilization; a simple yearly application of compost around the base of the tree is sufficient to supply necessary nutrients. These trees should be pruned in late winter or early springtime, before new growth pushes out for the year. Simply remove dead, damaged, diseased, or crossing branches to maintain a healthy shape and structure. These trees can develop weak branch attachments, leading to breakage in high winds. Regular pruning (about once a year) is recommended to prevent this issue.

Harvesting Hackberries
All species of Hackberry produce edible berries (which share texture characteristics with nuts), though some species do produce fruits that tend to be a little sweeter than others. Species that are commonly cultivated for fruit harvesting include Celtis occidentalis, Celtis laevigata, and Celtis australis. Hackberries are small, hard fruits made of sweet tissue around a hard seed. They are commonly harvested in fall, when the fruits are pea-sized. They will vary in color from dark maroon to orange to brown, and can either be picked off of trees or branches can be shaken to release the fruits. After harvesting, these fruits can be used in  a number of ways. They have a candy-like taste, are sweet and crunchy, and have a flavor reminiscent of date or black tea. Seeds are nutty. They can be boiled down and turned into a sugar syrup, made into a nut milk, or ground up (seeds and all) for mixing with other foods.

Propagation

Celtis can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. Propagation of Celtis trees by cutting is somewhat difficult; the cuttings do not always root, and success rate is usually pretty low. To propagate your tree, follow the instructions below:

Propagating Celtis by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Celtis by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a plastic bag or other sealable container, sand, a bowl, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds. The fruits on Celtis  plants are pretty easy to spot, they can be maroon, red, orange, or brown and are left behind after flowers have faded. These fruits can be harvested by hand from their attachments, scavenged from the ground under trees, or branches can be shaken to release them. Once they are off the tree, ferment them for three days in a bowl of warm water to release the skin and pulp from the seed itself. Remove and rinse seeds after fermenting, and lay them out.
  3. Celtis seeds must be cold-stratified before planting to mimic the natural processes that lead to germination. Place seeds in a plastic bag or other sealable container filled with moistened sand and bury them a bit in the substrate. Place the container into the refrigerator or other space that stays between 38 and 41 degrees Fahrenheit. Leave seeds for between 60 and 90 days, and then remove them from their sandy bed.
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a half inch to an inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 60 to 90 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Hackberries turn various shades of colors when ripe, including dark maroon, red, orange and brown.
Celtis seeds are hard and light in color.

Problems and Pests

These trees are generally pest and disease resistant, though they may occasionally suffer from issues with:
  • Aphids
    • Asian Wooly Hackberry Aphids
  • Leafhoppers
For more information on these pests and diseases, see the following links:
​

Gallery

The berries on Celtis pallida are small and orange, and provide a great food source for local birds.
Hackberry trees are useful shade trees with gorgeous canopies.
Celtis sinensis 'Green Cascade', also known as the Weeping Chinese Hackberry.
Hackberry trees are wonderful front yard or street trees.
Celtis trees produce small white flowers.
These trees are commonly planted in parks and other public areas due to their ease of care.

Videos

The low-down on these great deciduous trees.
Learn about these little-known fruits.
Hackberry trees are important ​winter food sources for local birds.
Learn about some of the drawbacks of these trees,
Learn how to identify these trees and learn about an associated disease.
Learn about Hackberry trees.

Resources

Native Hackberry Trees - A Beginner's Guide
How to Plant and Grow Hackberry
What to Know about Hackberries
Hackberries
Wikipedia: Celtis
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 230, Celtis
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
​