Zelkova

( zell - KOE - vuh )

At-A-Glance Information

This genus of deciduous trees is native to southern Europe, and southwest to eastern areas in Asia. Species form shrubs to large trees with dark brown, smooth bark and green foliage. Inconspicuous flowers bloom in clusters in lower leaf axils of young branchlets; blooms are ​greenish-yellow to cream colored. Autumn color is yellow to reddish-orange, varying depending on climate factors. Healthy trees have the best autumn colors. Use these trees as shade trees, street trees, specimens, or simply to provide background foliage and pops of fall color in the landscape. 

Zelkova species and Varietals

The genus Zelkova includes six species and is a member of the plant family Ulmaceae. The best growing zones for Zelkova are 3 through 21. To find your zone, click here: Zone Map.

Zelkova abelicea (Cretan Zelkova, Abelitsia)
This species is endemic to Crete, and is endangered. These medium-sized trees range in height from 10 to 16 feet tall. These trees produce suckers 

Zelkova carpinifolia (Caucasian Zelkova, Caucasian Elm, Zelkova)
This species forms a medium-sized to large deciduous ornamental tree that reaches between 66 and 115 feet tall.
Zelkova serrata (Sawleaf Zelkova, Japanese Zelkova, Keyaki, Keaki)
​This species of deciduous trees is commonly called Sawleaf Zelkova, and is native to eastern Asia. They require full sun and moderate to regular water to grow well, and are wonderful shade trees once established. Zelkova is related to Elms, but is much less susceptible to the diseases that plague that genus. They reach 60 feet tall or more and have an equal spread. Bark is smooth and gray, and leaves are green and a bit rough-textured. Fall color ranges from yellow to red to brown. This species typically puts on a bit over a foot in height each year.​
'Halka'
Looks a lot like American Elm.
'Green Vase'
Narrow vase-shaped tree; a vigorous grower.
'Musashino'
To 45 feet tall and 15 feet wide.
'City Sprite'
Compact, ovular tree to 25 feet tall.
'Village Green'
Vase-shaped tree with green foliage.
'Wireless' ('Schmidtlow')
Compact tree to 25 feet tall and 35 feet wide, with great red fall color.

Zelkova sinica (Chinese Zelkova)
This species is native to southeastern China, and is a well-known landscaping tree in its native range. They are also used as street trees in Europe and the United States. 

Caring for and pruning zelkova Trees

Zelkova trees thrive in full sun; they prefer to receive between 6 and 8 hours of direct sun each day, and will perform best and grow the fastest in this exposure. These trees are resistant to wind and air pollution, making them wonderful for urban landscapes and planting along roads. Make sure that there is enough soil depth available to accommodate for the tree's deep taproot, which extends as far into the soil as the tree is tall. Ensure that soil is well-draining before planting; if soils are compacted or overly clayey, amend the planting site with plenty of organic material and/or sand before installing. They prefer soils to be slightly acidic to neutral (with a pH of between 6.0 and 7.5). Avoid waterlogged conditions, and do not plant these trees in areas of the landscape that have any flooding problems. Apply a thick layer of mulch around the base of trees to suppress weed growth, increase soil moisture retention, and help to regulate soil temperatures. Water newly planted trees regularly to help them establish a strong root system. Mature trees are more drought-tolerant, but will still need extra waterings, including deep waterings, during the growing, flowering, and fruiting seasons.

​Pruning is best done in late winter or early springtime, while the tree is still dormant and before new growth has pushed out for the year. At this time, remove dead, damaged, diseased or crossing branches and open up the canopy to increase airflow and sunlight penetration. Shape the tree to maintain an open, vase-like structure. Young trees should be pruned after planting to encourage a strong central leader to emerge with well-placed scaffolding. Remove any seedlings that grow around the base of trees. Organic compost can be used yearly, applied in springtime around the base of trees to improve and maintain soil structure and nutrients. Otherwise, these trees don't typically need fertilizing. However, if trees seem to be struggling or not growing well, they may benefit from an application of a balanced, slow-release fertilizer applied in springtime to support the season's growth.

Propagation

Zelkova trees 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. To propagate your Zelkova tree, follow the instructions below:

Propagating Zelkova 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 4-6 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 Zelkova 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 paper bag, 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 seeds of Zelkova trees are contained inside of the drupe fruits produced in fall. They have hard, dry flesh and contain between one and several seeds each. Bring fruits indoors, cut them open, remove the seeds and rinse them under lukewarm water to rinse off remaining flesh. Then, set them out to work with them or place them in an airtight container and store them in a cool, dark, dry place (a refrigerator works well) for up to a year. 
  3. 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 quarter inch to a half-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 7-14 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.
  4. 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.
Zelkova fruits are called drupes.
Each drupe fruit typically contains between 1 and 4 seeds.

Problems and Pests

Zelkova trees are generally considered to be pest and disease-resistant, but they can experience issues with the following, especially if under stress:
  • Aphids
  • Scale Insects
  • Bacterial Canker
  • Elm Yellows
  • Phytophthora Stem and Collar Rot
  • Leaf Rollers
  • Spider Mites
For more information on these pests and diseases, consult the following pages:
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Gallery

Zelkova has beautiful fall foliage that varies in color from dark burgundy through to yellow.
Zelkova trees make great lawn shade trees, and can also do well as street trees.
These trees are typically leafless from fall through spring.

Videos

All about these wonderful landscape trees.
Japanese Elms make great bonsai subjects.
Learn about these great trees.
Learn how to identify Zelkova serrata trees.

Resources

Care Guide for the Japanese Elm Bonsai Tree
How to Grow and Care for Japanese Zelkova Trees
Wikipedia: Zelkova
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 659 - 660, Zelkova serrata
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!
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