In Bloom: How Greenery and Landscaping Work with CPTED
Just like all other organisms, humans are influenced by the environment around them.
This fact of nature is an essential lever in crime prevention through environmental design (CPTED) that security practitioners can use. Landscaping and other natural elements help establish boundaries, visibility, and overall order—which in turn can have an impact on how people behave and react to the area.
Secure facilities present several layers of security checks, sometimes both inside and outside of a building. Fences, staff or student IDs, key fobs, video cameras, weapons or metal detectors, and many other solutions are familiar sights to us, influencing us to obey the rules and perhaps even be on guard in case someone else decides to break those rules.
But a hard security posture can be off-putting to legitimate site users. Incorporating natural elements—from flowers and trees to ditches and hills—into a larger crime prevention strategy and security program can help soften the harder edges of an area that may already be outfitted with metal fences, access control keypads, or guards.
It’s Good to Be Green
“Using green scaping and natural elements within CPTED enhances security while maintaining aesthetic and environmental harmony,” says Michael White, CPP, a risk assessment consultant.
He adds that using natural elements can help achieve multiple CPTED objectives.
Natural surveillance. When designing a space, enhancing visibility allows the people using a space to feel a sense of openness compared to the confines of a building. It also turns those individuals into extra pairs of eyes for surveillance efforts, able to spot if something is amiss or if there is someone who may be trespassing.
Landscaping can enhance visibility or intentionally block sightlines, which can either expose or hide activities, according to White.
“For example, low hedges and strategically placed trees allow for natural surveillance, where residents or passerby can easily observe the area, reducing opportunities for criminal behavior,” he says.
Low-growing plants can be used along pathways to improve visibility. Certain trees and bushes can provide shade and a pleasing aesthetic, as long as they are maintained. White also recommends keeping grasses, hedges, and tree branches well-trimmed to avoid creating areas where people can hide behind or within vegetation.
Depending on the environment and the intention (surveillance versus barriers), Mark Schreiber, CPP, president and consultant for Safeguards Consulting, says that vegetation that grows upward (i.e., grasses, shrubs) should be kept a height of 2 to 3 feet or lower. Anything hanging downwards, like tree branches, should droop no lower than 7 to 8 feet from the ground, he adds.
Natural access control. Pathways and barriers support multiple CPTED concepts by influencing movement and indicating which areas are permissible to people.
Trees, bushes, shrubs, and hedges can complement hardscaping elements, such as fences, concrete barriers, and walls. Together, these elements create a layered border that subtly reinforces access control while remaining aesthetically pleasing.
Territorial reinforcement. Using landscaping to clearly define areas—such as pathways, well-maintained grass lawns, or flower beds—lets people know that an area is cared for, White adds.
“This indicates to potential offenders that the space is regularly attended and monitored, thus deterring criminal activity,” he says.
The barriers also indicate to people that an area is separate from outside and public spaces. There are also less traditional ways to indicate that an area is private property.
“When we don't have or don’t want to put up walls or fences, we can put up other measures of territorial reinforcement. Signage is a very common solution,” Schreiber says.
Smaller landscaping features, such as hedges or knee-high walls softened by a flower bed or well-maintained grass lawns, can also delineate a border. These elements send the message that “clearly someone put this here for a reason,” Schreiber says. “I’m not going to walk through this hedge. I’m going to walk around it. And now I know, as a human, that the rules have changed. I can’t treat the rules of this open space or this public park the same as this property because the territory has been reinforced or the ground has been laid, so to speak.”
Activity support. Using greenery can also help define the purpose of an area, such as open lawns that indicate a recreational area and dense hedges that work as boundaries for areas that are off limits to most.
“The intentional use of landscaping can guide people’s movements and behavior, subtly indicating where they are allowed to be and where they are not,” White says.
Other examples include rain gardens or bioswales, which provide a solution for both water runoff paths and barriers.
When conducting a CPTED assessment with her clients, consultant and retired sergeant for the Waterloo Regional Police Service Kelly Prebble likes to ask them how they feel in certain spaces. This gives Prebble and her clients additional input on the current state of a space and how it can be improved.
Improvements big or small can help generate positive interactions with an area’s stakeholders and even the larger community, further deterring opportunistic criminals. “It grows from there,” Prebble says.
When staff, students, or the community see a change, Prebble notes that “they’re more eager and more willing to come out and participate in other events. Whether that’s building birdhouses for the kids in the community, having a barbeque day, building raised garden beds, or involvement in an art project, like a mural.”
Target hardening. Barriers created by plants again come into play, helping fill in any gaps left by a facility’s more vulnerable areas, such as windows. This can help block those trying to look in or increase the distance between the glass and the person outside.
Other landscape features, like trees or even large boulders, can be used to reinforce appropriate actions in an area and prevent vehicles from attempting to get closer than desired.
Maintenance, Maintenance, Maintenance
Like all other aspects of security, maintenance of environmental elements can make or break the safety of an area or an organization.
“When we have maintained properties, less crime occurs typically in those areas,” says Herb Ubbens, CPP, PSP, president of Paratus Consulting Group. “More people gather, so now we’re talking about natural surveillance. With more people around, people are less inclined to commit crimes.”
Maintenance perhaps trumps the input of design in CPTED because failure to keep an area well-kept indicates neglect. If no one cares for a space, then people assume that no one owns it or is invested in it.
“If you take any type of environment, no matter how good the design is, and you just don’t maintain it, and it overgrows and it becomes a mess, it’s kind of like graffiti,” Schreiber says. That lack of care means that others will feel free to do whatever they please, he adds.
For example, the combination of landscaping and good design can help with natural surveillance, allowing someone to observe his or her surroundings while enjoying shade from a tree on a warm, sunny day. Without proper maintenance of those trees and plants, the risk to an area increases. Neglected areas become attractive for opportunistic criminals looking for a space where their activities will go unnoticed.
In comparison, legitimate users of a space—visitors, staff, students, and so on—are more likely to be discouraged from visiting an area that lacks maintenance. White adds that signs of neglect can go as far as to remind others of horror movies, making those legitimate users wary and uncomfortable because of the state of the site.
Perception must be addressed in the design and maintenance of a space, even before people enter an area, according to White. Removing overgrowth, graffiti, litter, or other signs of neglect discourages opportunistic criminals from using the space.
Beyond maintaining clear sight lines and preventing hiding places, keeping vegetation trimmed also helps prevent walkways from being blocked or obstructed, which decreases the likelihood of an accident or other liability issues.
White recommends designing and implementing a routine care plan that includes regular pruning, trimming, and upkeep. This plan should also account for any environmental changes brought on by the shift in seasons, such as sudden growth rates in the spring and summer or impacts from heavy rains or snowstorms. Use signage or strategically placed garbage bins to prevent litter from accumulating on the grounds.
The Right Time and Place for Plants
It’s easy to imagine how a vivid rose bush would win a beauty contest if the other contestant were a chain link fence, so it’s no surprise that plants and other natural elements are selected for use in CPTED for both their functional and aesthetic benefits.
“Natural elements are visually appealing and can improve the overall atmosphere of a space, creating a welcoming environment,” White says. “This can encourage positive use of the area by legitimate users, deterring criminal activity.”
Enhancing the aesthetic appeal of a property can soften the harder edges of most buildings, notes Sarah Poskanzer, managing director of security and emergency management services for TRC Companies, Inc.
“A lot of public spaces or public buildings, whether they’re government facilities or schools, while they have to have security involved, they also want to be somewhat welcoming. And plants and vegetation help do that,” she says. Plants “create visual interest, and they create that welcoming environment that, if used appropriately, will guide people to the right entrance and keep them away from other places.”
Beyond good looks, natural elements also offer environmental and cost benefits. Plants support air purification and noise reduction, and they tend to be more cost-effective in the long run compared to manmade barriers and features, according to White.
And as the seasons or a site’s needs change, plants’ flexibility can allow for easier changes and alterations with less cost than required to move or adjust permanent physical barriers.
“For example, trees can grow over time to provide more coverage or be selectively pruned to adjust for sightlines,” White says.
Working with a good landscape architect or designer can be useful because they can draw on several design principles and are familiar with plants that are better suited to certain climates and purposes, Schreiber adds.
Security practitioners could determine that they need territorial reinforcement that delineates a clear border for the facility—such as by using hedges, bushes, or trees. They could then work with a designer to decide what options might be most appropriate for the environment the facility is in, Schreiber says.
This coordination helps reach an agreement that achieves both CPTED and landscaping goals.
“In essence, it can be done many different ways,” Schreiber says. “There’s not one plant, one style that works. It’s what's appropriate for that environment and the partnership of the landscaping design with the security design together.”
Sara Mosqueda is associate editor for Security Management. Connect with her on LinkedIn or via email at [email protected].
