Light Pollution: Landscape Plants Affected by Bright Advertising Lights

Trees affected by light pollution

Bright golden yellow light emitted from advertising bill boards or street lights can adversely affect landscape plantings. Few of us give thought to “light pollution”, but three-fourths of Americans grow up without having seen the Milky Way. Laser light shows and fireworks have replaced the wonders of the starry sky. Human health can be affected by a lack of darkness, and other natural systems ranging from migrating birds to nesting sea turtles to disrupted cycles for oak and sycamore trees next to billboards are also becoming confused and threatened.

Bright advertising lights are not the same as landscape lighting. Ornamental landscape lighting is not intense enough to damage plantings. Benign types of landscape lighting include fluorescent, incandescent, low voltage, mercury vapor or metal halide lights.

Plant Symptoms resulting from bright intensity of high-pressure sodium lighting

• Disrupted life cycles 
• Accelerated plant growth 
• Increased leaf size 
• Faster flowering and fruiting 
• Shoots that over grow, especially those nearest the light 
• Delayed dormancy 
• Leaves triggered to sprout too early 
• Leaves triggered to hang on late, beyond the normal growth period 
• Spring die-back resulting from delayed dormancy the fall before 
• Clubroot development in some plants (cabbage) 
• Alters the migration of night pollinators of landscape plants 
• Insect decline due to “fixated or capture effect” of lights on insects  

up-lighting is bad

 Crabapple LandscapExperts can help you with a solution. We can install deflectors that will direct the lights away from your plantings. Just telephone your Rep at 770-740-9739.    

Digging Deeper

The International Dark-Sky Association http://www.darksky.org/about-ida mission is to preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting. Their PDF is informative: http://www.darksky.org/assets/documents/education/MiniPageLightPollution.pdf

Images thanks to http://faculty.northgeorgia.edu/jjones/astr1020home/lightpollution.html