While honey locust trees have been admired for centuries, these trees naturally have thorns and pods that cause major cleanup issues for homeowners. Podless, thornless (and non-messy tree) honey locusts now exist, thanks to the magic of cultivars.
Although the cultivar name is Suncole, the plant is usually referred to by its trademark name, Sunburst. Sunburst honey locust is a member of 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. These are fast-growing trees. This tough specimen is also tolerant of various harsh environmental conditions like drought, pollution, salt, compacted soil, heat, and alkaline soils.
- Botanical Name: Gleditsia triacanthos var. inermis "Suncole"
- Common Name: Sunburst honey locust tree
- Plant Type: Deciduous tree
- Mature Size: 30 to 40 feet tall with up to a 20-foot spread
- Sun Exposure: Full sun
- Soil Type: Most types
- Soil pH: Acidic, alkaline, or neutral
- Bloom Time: Spring, summer
- Flower Color: Greenish-yellow
- Hardiness Zones: 4 to 9
- Native Area: North America
How to Grow Sunburst Honey Locust
This tree attains a mature height of 30 to 40 feet, with a spread a bit less than that. It is slow to leaf out in spring, but, when it does, its leaf display is a sight to behold. The new foliage starts out yellow, then morphs to a still attractive greenish-yellow, before assuming a plainer light green shade in summer. When it is time for the fall-foliage display, the leaves return more or less to the yellow color that marked them in spring. So, like Bloodgood Japanese maple, it offers colorful foliage for at least two different seasons.
Full sun is preferred by the thornless honey locust tree, although young trees will grow in partial shade.
The honey locust tree is a hardy tree and can grow well in different types of soil. Loam, wet, well-drained, sandy, acidic, and even moist rich soil work well for the honey locust tree. This tree is also salt tolerant.
Honey locusts have a moderate tolerance for flooding, drought, and other adverse conditions. They live in 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 root provides proper water for a new tree. Adjust watering based on the local rainfall.
Temperature and Humidity
The honey locust is able to grow in a variety of soils, temperatures, and moisture conditions. The honey locust cannot survive exposure to temperatures below -33 degrees Fahrenheit.
Older trees rarely need additional irrigation or fertilizing, especially if they are in an irrigated, fertilized lawn. For newly planted trees, you can try an evenly balanced 10-10-10 or 20-20-20 granular, stake, or liquid fertilizer. An organic fertilizer like manure is another good option.
Propagating Sunburst Honey Locust Trees
This tree can be propagated in different ways. Some people take cuttings and use rooting hormone to produce roots and a new tree. Propagation of high-quality clonal stock can be achieved by grafting, budding, and cuttings from hardwood, softwood, and roots. In many cases, thornless or podless varieties are grafted onto the rootstock of honey locust.
Since Sunburst honey locust trees are podless, you will have difficulty trying to propagate this tree by seed (although as Sunburst trees age, some may eventually make seeds in their later years).
These trees can function as specimen plants or as street trees. As with kiwi vines, these provide a wonderous spring-foliage season display. Leaf peeping should not just be for the better-known fall-foliage season, honey locust trees leaf colors pop in spring.
Because their canopy is relatively loose and airy, they do not make especially effective shade trees if you are seeking deep shade. However, this same quality makes them good lawn trees. The problem with most large trees is that their canopies cast too much shade to grow grass beneath them (unless you grow a shade-tolerant grass). Grass grown under the relatively open canopy of honey locust trees has a better chance of receiving adequate sunlight.
Honey locusts served many practical functions long before Sunburst was developed as a good landscaping tree. The species plant was used traditionally in the making of railroad ties and fence posts, for example. Given that such products made from its strong, durable wood became fixtures in everyday life, it is not surprising that many towns in the U.S. have a "Locust Street."
These trees are frequently attacked by insects such as webworm and borers, but gypsy moths tend to leave them alone. They are also attacked by diseases such as leaf spot and canker disease. Honey locusts are deer-resistant plants.
Varieties of Honey Locust Trees
There are various kinds of locust trees. For example, black locusts are classified as Robinia pseudoacacia. But even within the Gleditsia genus, there are:
- Gleditsia triacanthos, thorny locusts
- Gleditsia triacanthos var. inermis, thornless locusts
G. triacanthos is practically defined by the presence of dangerous thorns, thus the common name. Likewise, with the inermis variety, people were so impressed that these trees lacked such imposing spines that they took to calling them simply "thornless locusts," a fact reflected even in the Latin name. To avoid exposing tender skin to accidental piercings from sharp thorns, only inermis is promoted for landscaping use.
While this solves one landscaping problem related to safety, it does not solve another associated with Gleditsia, whether thorny or thornless: the mess created when the seed pods drop to earth in fall—thus all the hoopla over the development of types of thornless honey locusts that are relatively podless.
Sunburst is not the only podless type; Shademaster is another example. Whereas Sunburst starts out with yellow leaves, Shademaster's color evolution conforms more to the norm, beginning in spring with green and ending with golden-yellow fall foliage.
The development of podless types was a major coup and elevated thornless honey locusts to elite status as non-messy trees, ideal for low-maintenance landscaping. In terms of the mess created by fallen leaves, they were already less messy than most. The small size of their leaves means that when they fall, they are less likely to smother lawn grass, the way larger leaves do.
But now, with the availability of the Sunburst and Shademaster varieties, you have the option of planting a specimen that is about as non-messy as a tree can possibly be—a relief as seed pods can be something of a cleanup nightmare. When the seed pods rain down in fall, the grass beneath is blanketed with what looks like flat, brown snakes. About the only use for them is in crafts, such as in creating natural kissing balls.