Thorny Solutions: Bushes and Other Plants That Deter Trespassing

Thorny bushes and other landscape options can help keep out trespassers

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Hawthorne and other thorny bushes deter trespassers


Reinforced planters, light posts and benches are often used to enhance site security (click for video), making it impossible for a bomb-laden automobile to get close to a building. But what landscape options are available for companies that are concerned about individual trespassers accessing high-security areas? Some trees and shrubs are, in fact, quite useful for reinforcing security. Dennis Carmichael, landscape architect and principal with EDAW in Alexandria, Va., highlights some plantings that can provide an attractive and effective deterrent.

Trees Hawthorne This dense hedge grows 20 to 25 feet high and produces fragrant pink and white flowers. But beware the sharp thorns, which can range from 1 to 5 inches in length
Hardy Orange A fruit-bearing tree often used around prisons, hardy orange grows 15 to 20 feet high and wide and is covered to the ground with lacerating thorns.
Black Locust Resistant to rot and pollution, black locust produces creamy white flowers and a pair of short thorns at the base of each leaf.
ShrubsPyracantha This thorny evergreen shrub produces red, yellow or orange berries in the fall.
BarberryAlso referred to as "sticker bushes, " these shrubs are characterized by their distinctive three-spined thorns.
Roses Some varieties of this garden favorite will grow into a dense thicket that is impenetrable to trespassers.

WEED WHACKING The Homeland Security department recently announced a new operational target: Carrizo cane. It might sound like the name of a South American warlord, but it’s actually a weed. Also known as elephant grass, Carrizo cane is a particularly tall and densely growing plant that has taken over areas of the U.S. border with Mexico, blocking waterways, damaging bridges and potentially providing security threats or illegal aliens a cover through which to enter the United States.

landscaping as part of building security
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