By: Amy Grant
The honey locust ‘Skyline’ (Gleditsia triacanthos var. inermis ‘Skyline’) is native to Pennsylvania into Iowa and south to Georgia and Texas. The form inermis is Latin for ‘unarmed,’ in reference to the fact that this tree, unlike other honey locust varieties, is thornless. These thornless honey locusts are great additions to the landscape as a shade tree. Interested in growing Skyline honey locusts? Read on to find out how to grow a Skyline locust tree.
Honey locust ‘Skyline’ can be grown in USDA zones 3-9. They are rapidly growing shade trees lacking the up to foot-long (0.5 m.) thorns and, in most cases, the large seed pods that adorn other honey locust trees.
They are rapidly growing trees that can grow up to 24 inches (61 cm.) per year and attain a height and spread of about 30-70 feet (9-21 m.). The tree features a rounded canopy and pinnate to bi-pinnate dark green leaves that turn an attractive yellow in the fall.
Although the lack of thorns is a boon to the gardener, an interesting side note is that the thorned varieties were once called Confederate pin trees since the thorns were used to pin Civil War uniforms together.
Skyline locusts prefer rich, moist, well-draining soil in full sun, which is at least 6 full hours of direct sun. They are tolerant of not only a wide array of soil types, but also of wind, heat, drought, and salinity. Because of this adaptability, Skyline locusts are often selected for median strip planting, highway plantings, and sidewalk cutouts.
There is little to no need for special Skyline honey locust care. The tree is so adaptable and tolerant and easy to grow once established that it basically maintains itself. In fact, areas suffering from urban air pollution, poor drainage, compact soil, and/or drought are actually perfect areas for growing Skyline honey locusts within USDA zones 3-9.
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The term “locust” can apply to several different species of trees with legume-like seed pods.
Locust trees are from the Fabaceae (legumes or pea family) family native to North America. Different locust trees are classified as part of the Gleditsia or Robinia genera. Meaning locusts can be trees or shrubs.
The most popular types of locust trees in North America are called black locust and honey locust.
In this article you’ll find all you need to know about their uses, popular varieties and related planting processes.
The Victorians even believed there were secret meanings behind locust trees and other flower and tree species.
|Gleditsia triacanthos var. inermis||Synonym|
|Gleditsia triacanthos f. inermis||Synonym|
|Plant Habit:||Tree |
|Life cycle:||Perennial |
|Sun Requirements:||Full Sun |
|Water Preferences:||Mesic |
|Soil pH Preferences:||Neutral (6.6 – 7.3) |
Slightly alkaline (7.4 – 7.8)
Moderately alkaline (7.9 – 8.4)
|Minimum cold hardiness:||Zone 3 -40 °C (-40 °F) to -37.2 °C (-35) |
|Maximum recommended zone:||Zone 8b |
|Plant Height :||60 to 80 feet (18-24m)|
|Plant Spread :||60 to 80 feet (18-24m)|
Other: 12 to 18 inch long, flat pod
|Fruiting Time:||Late summer or early fall |
|Flower Color:||Green |
Other: Cream to greenish-yellow or greenish-white
|Bloom Size:||Under 1" |
|Flower Time:||Late spring or early summer |
|Underground structures:||Taproot |
|Suitable Locations:||Street Tree |
|Uses:||Shade Tree |
Useful for timber production
|Resistances:||Deer Resistant |
|Pollinators:||Various insects |
|Miscellaneous:||Tolerates poor soil |
Leaves so often take a back seat to the more showy and colorful flowering blooms and fruits. While we wait for spring to arrive, let's take a look at leaves as the star attraction.
The wild, mother species of Common Honeylocust is usually full of nasty thorns on the trunk, branches, and larger twigs. There are some wild thornless trees out in nature also. Cultivars have been taken from the thornless variety, but some cultivars have come from buds high up on the more common thorned trees. The tree grows in upland sites from central Pennsylvania to all of Louisiana and eastern Texas up to eastern Nebraska and Iowa to spots in southern Wisconsin and northern Illinois through far southern Michigan back to Pennsylvania. It is fast growing of about 2 to 2.5 feet/year and lives about 150 to 200 years. The species is in between being monoecious and dioecious where one tree will have mostly one gender of flower and a little of the other. Therefore, some trees produce a lot of the brown, woody, curving pea-like pods to about 12 inches long with big brown seeds inside with thick seed coats, and other trees few or not-so-many pods. It is easy to transplant despite that when older it can develop a taproot or deep lateral roots. The thornless and mostly podless cultivars are now being the most commonly planted shade & street tree, now that Green Ash has met disaster with the Emerald Ash Borer. The cultivars make neat, clean, windfirm trees. One can easily mow the fallen leaves into the lawn or they make a good mulch for planting beds for the winter.
The thorns on this plant can grow over 20cm long! I didn't measure these while I was out in the field, but I can tell you, they are imposing! It's been said that in the past these were occasionally used as a substitute for nails. I can believe it!
The branch structure on these plants is non-uniform and rather untidy. One individual (main) branch can be quite long, while another may be just a bit over stub length. This trait is most apparent in younger trees.