Plants Sleep Too!

My new awareness of light pollution

Do you ever have one of those moments when you learn about something that causes a complete reset in your thinking? I had one several years ago when I noticed certain plants in my garden were covered in bees and other pollinating insects, while others were left alone. Mountain mint, Pycnanthemum muticum- a fantastic plant with flowers that are not particularly vibrant or showy - was alive with a variety of bee species. A neighboring plant, Hemerocallis fulva (orange Day Lily), with its show-stopping blooms, had very few visitors. Similarly, my native Smooth Hydrangea, Hydrangea arborescens - was literally shaking with fat bumble bees shimmying their furry bodies across the flat blossoms. But the blue Hydrangea macrophylla? Quiet and still..

Our insects need our native plants – it’s as simple as that. Thus my native plants journey began and I’m still learning from this community every day.

I recently attended a presentation called ‘Preserving Dark Skies’ given by Steve Mariconda of DarkSky New Jersey. I was certainly aware of light pollution and I knew enough to turn off unnecessary outdoor lights that attract and kill moths and other insects at night, but I hadn’t really understood the true scope of the problem with lighting until I heard this presentation.

DarkSky New Jersey is the local arm of DarkSky International - the leading global authority on combating light pollution. They are doing very important work and I encourage you to do a deep dive into this admirable, changemaker organization when you are ready, but I’m going to try to distill the main actionable points.

Light Pollution is described as the biggest environmental problem no one has heard of.

"Plants and animals depend on Earth’s daily cycle of light and dark to govern life-sustaining behaviors such as reproduction, nourishment, sleep, and protection from predators. Scientific research suggests that artificial light at night has negative and deadly effects on many creatures, including amphibians, birds, mammals, insects, and plants.” – DarkSky International

LINK: DarkSky.org 

The Problem: 

Insects are hugely impacted by artificial light. We’ve all seen moths and other insects drawn to our porch lights at night. Moths fly in circles, attracted to the light where they eventually bash themselves to death. I recall as a child seeing countless insects outside our home  around the lights, but today there are far fewer nighttime visitors. The insect apocalypse is real.

Migrating birds - most birds migrate at night and they navigate by moonlight and starlight. Artificial light disrupts cycles and can cause birds to go off course. Think of the light projected from large cities with tall buildings illuminated all night long - millions of birds die each year colliding into skyscrapers and towers. 

Humans: More research is needed on how outside artificial lighting affects our health, but we do know that there is a clear link between light exposure at night and the disruption of our circadian rhythms and sleep. At the very least, we can’t see the stars! According to DarkSky, 80% of North Americans are unable to see the Milky Way from their homes. We are losing our connection to the natural world around us.

Plants: Yes, plants need to sleep too! Constant lighting can cause premature blooming, excessive growth, changes in leaf structure and alteration on when to drop leaves in the fall. 

That’s a lot of scary stuff and much of it was new to me. I admit it depresses me to write about this and at times I feel overwhelmed and powerless. Here’s the good news: we can make some very simple changes right away in our homes and I am heartened to know there is a group of scientists and social advocates working to implement sweeping changes to reduce light pollution - globally!

The Solutions: 

Quick fix - swap out cool, white or blue LED blubs with warm-white or yellow/orange-toned bulbs. 1000-3000 kelvin is optimal.

• Make sure your lights are pointed downward, targeting the small area you need to illuminate. Fixtures that point upwards or allow light to spread out horizontally are problematic and wasteful and should be swapped out for those that point down. 

• Turn lights off when not needed (or install motion-sensor lighting). 

• Close curtains or blinds at night to stop interior lighting leaking outside.

All these changes save money and resources too so it’s a win-win.

More good news: Local governments are adopting ordinances to reduce light pollution. While the small changes we make in our own homes are very important, we need help with the big offenders such as sporting complexes, corporate parks and shopping malls, where the lights never seem to go out. Cities in Arizona, Texas, and Tennessee have already adopted regulations to limit unnecessary lighting. Some of our National Parks are leading the way to protect our night skies and we can join the movement.