The Japanese Zelkova (Zelkova serrata) has come to some fame as a stand-in for the disease ravaged American Elm. While it can never truly replace the American Elm, it is a lovely tree on its own merits.
This tree is a native of East Asia that has been in use in ornamental horticulture in the west since the 19th century. It has only been in the past fifty years or so, however, that the zelkova has skyrocketed to popularity due. This is largely due to its similarity in form and stature when compared with the American elm and the fact that it is highly resistant to Dutch Elm Disease and the Elm Leaf Beetle.
Both trees are vase-shaped and can grow to have a 100-foot spread while offering pleasing fall color. The two trees are also in the family Ulmaceae but from different genera. When looking to replace the stately American elm as a shade tree or street tree, people look towards the Japanese Zelkova, and it does well enough, but it lacks in some significant areas.
The primary concern that Japanese Zelkova presents is how easily it breaks. A habit the species has is the tendency to grow multiple leaders while having very fragile wood. Having multiple leaders is a genetic weakness in the species that is somewhat solved in some available cultivars but not in the wild type. If searching for a Japanese zelkova, it is crucial to buy a tree with a single trunk or leader, or the tree will eventually experience breakage at the tree’s crotch later in its lifespan.
Another area the tree falls behind the American Elm in is ecology. As a non-native tree, Japanese Zelkova doesn't support native caterpillar species, isn't a host for the larvae of pollinating butterflies or moths, and doesn't provide food for birds.
If you are passionate about supporting native wildlife and ecology, as a substitute, consider planting a disease-resistant variety of American Elm or another native like a Black Cherry or Red Oak instead.
However, growing a Japanese Zelkova as a specimen, shade tree, or street tree is a good idea if the right tree is chosen and cared for properly. It can provide a beautiful shady location and a dazzling burst of color in the fall.
|Botanical Name||Zelkova serrata|
|Common Name||Japanese zelkova|
|Mature Size||50-80 ft. tall.|
|Sun Exposure||Full Sun|
|Soil Type||Average, Good Drainage|
|Soil pH||Prefers Neutral Soil|
|Hardiness Zone||USDA 5-8|
|Native Area||East Asia|
Japanese Zelkova Care
Although this is a versatile tree, be prepared to put in the maintenance, particularly when it comes to pruning. You will want to keep your Japanese zelkova from becoming damaged as this can cause more significant issues down the road.
The Japanese Zelkova thrives in full sun to partial shade. The sunnier the location, the better the fall colors will be.
One positive aspect to the Japanese Zelkova, and a reason it makes a terrific street tree, is that it tolerates drought very well and does not need much supplemental watering after it has been planted.
To establish the tree, give it a good thorough soaking weekly for the first season to the point of ground saturation. Infrequent, deep saturation is better than quick and often when watering newly planted trees.
Temperature and Humidity
The Japanese Zelkova is relatively cold hardy and can thrive in most temperate regions of the United States. The ideal USDA zones for the zelkova are 5 through 8.
Japanese Zelkovas require no regular supplemental fertilizer. If the tree is not performing well, it might be wise to amend the soil to provide a bit of a boost. Test your soil to establish the best type of amendments to handle any soil deficiencies that may be occurring.
The zelkova requires pruning to develop the structure to avoid breakage. While in the nursery, it is essential to select a tree that has a single leader. The species will continue to grow branches that bunch and split inward towards the leader, creating deep “V-Shaped” crotches. These branches need to be pruned yearly in the late fall through late winter to eliminate these extreme V-shapes.