Honey locust trees (Gleditsia triacanthos) have been admired for centuries, but the native species has thorns and seed pods that cause major cleanup issues, which limits its appeal for homeowners. Plant science has, however, given us a number of podless, thornless honey locust cultivars that are much more suitable for landscape use.
One such well-behaved cultivar is usually known by its registered trademark name, Sunburst. The official cultivar name is Gleditsia triacanthos var. inermis 'Suncole'; it was created through selective manipulation of a thornless variation of the native species. 'Suncole' has a pyramidal shape and is somewhat shorter than the native species, growing to about 40 feet vs. the 80 feet of the native tree. The podless/seedless characteristic derives from the fact that commercially offered trees are typically male cultivars. These are tough, fast-growing trees that tolerate challenging urban conditions, such as drought, pollution, salt, compacted soil, heat, and alkaline soils.
Honey locust is a member of the Fabaceae family (also known as the pea family), along with well-known landscape plants like lupine and wisteria. The compound leaves are fern-like, with a fine texture, and the branching pattern is relatively open and airy. The new foliage starts out yellow, morphs to a still attractive greenish-yellow, and turns a plainer light green shade in summer. When it is time for the fall display, the leaves return to the yellow color that marked them in spring.
|Common Name||Sunburst honey locust|
|Botanical Names||Gleditsia triacanthos var. inermis 'Suncole'|
|Mature Size||30-40 ft. tall, 30-40-ft. wide|
|Soil Type||Loamy, sandy, clay, silt|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Spring, Summer|
|Bloom Color||Green, yellow|
|Hardiness Zones||4-9 (USDA)|
|Native Area||North America|
Sunburst Honey Locust Care
This tree has few restrictions on how to grow it; the only place it struggles is in dense shade. It is an ideal tree to plant in locations where you want filtered shade rather than the deep shade created by many other landscape trees. It's a good choice for a lawn tree because it allows plenty of filtered light to enable grass to grow underneath it.
Keep the tree well-watered, and make sure to protect the trunk against damage from lawnmowers and other lawn equipment, as the bark is tender and prone to injury. Applying a ring of mulch such as shredded wood or bark chips around the base of the tree is a good idea, as it will keep mowers away from the trunk. Do not let mulch come in contact with the trunk, because doing so can damage the bark and introduce diseases and pests. Be careful not to create a mulch volcano.
The tree should be planted in a location where it gets full sun (at least six hours of direct sunlight on most days).
Honey locust can grow well in different types of soil. Loam is ideal, but the trees are also quite tolerant of sand or clay. This tree is also tolerant of salty soils.
Honey locusts have a moderate tolerance for flooding, drought, and other adverse conditions. They thrive in both moist or dry soil. Trees should be watered as soon as they are planted and weekly for the first year. A one-hour trickle that slowly saturates the roots provides adequate water for a new tree. Adjust watering based on the local rainfall amounts.
Temperature and Humidity
The honey locust is able to grow in a variety of climate conditions, but it will perish if exposed to temperatures below minus 33 degrees Fahrenheit.
Older trees rarely need additional irrigation or fertilizing, especially if they are in an irrigated, fertilized lawn. For newly planted trees, apply an evenly balanced 10-10-10 or 20-20-20 granular or liquid fertilizer, or a fertilizer stake. For the amount to use, follow the product label instructions. An organic fertilizer such as manure is another good option.
Types of Thornless Honey Locust
Thornless honey locusts are all members of the inermis variation, and the podless/seedless varieties are typically male cultivars. Some other varieties to consider include:
- 'Imperial' (Gleditsia triacanthos var. inermis 'Impcole'): This is a more compact and thornless cultivar (35 feet) that produces a few seed pods.
- 'Moraine' (Gleditisia triacanthos var. inermis ‘Moraine’): This seedless male cultivar has a more rounded head with small dark green leaves that turn golden yellow in fall. It grows up to 50 feet tall.
- 'Northern Acclaim' (Gleditsia triacanthos var. inermis 'Harve'): This seedless male cultivar is cold hardy to USDA zone 3. It is more cold hardy than other cultivars and grows 35 to 50 feet tall.
- 'Perfection' (Gleditsia triacanthos var. inermis 'Wandell'): This is a seedless male cultivar that grows 45 feet tall.
- 'Street Keeper' (Gleditsia triacanthos var. inermis 'Draves'): This cultivar has a more narrow pyramidal growth habit with attractive dark green foliage that emerges light green in spring (20-foot spread); it produces some seed pods.
Mature honey locust trees need little pruning except to remove dead or diseased branches, but until they are mature, you should prune them every five years or so to shape them as desired. This typically means keeping the canopy relatively open and airy. Branches that cross and rub can be susceptible to developing canker, which can spread and kill a tree. The best time to prune is in late spring to fall when sap flow has lessened somewhat.
Propagating Sunburst Honey Locust Trees
The cultivar 'Sunburst' is a registered trademark that cannot be propagated.
Common Pests & Plant Diseases
Honey locusts are somewhat susceptible to a variety of insect pests, including mites and webworms. Pests are less likely to be serious problems if you keep the tree in good condition with adequate watering and by regularly removing dead and damaged branches. The tree can also be attacked by diseases such as cankers and root collar rot.
Are Sunburst honey locust trees messy?
This is a cultivar that was specifically bred not to shed thorns and seed pods so it's not a messy tree.
What is the lifespan of a Sunburst honey locust tree?
It can live 70 years or longer, provided it's planted in a sunny location.
Are honey locust tree roots invasive?
Honey locust trees have a taproot reaching deep into the soil (10 to 20 feet) and an extensive system of lateral, shallow roots that can interfere with lawn mowing.