Why Your Garden Should Be Dark at Night

A confession: I was a teenage astronomy geek. This hobby that gave me an awareness of how depressing it is to live in a city so brightly lit that you can count the number of stars in the night sky.

A documentary, currently streaming on Netflix, called The City Dark details just how many other problems lights cause that you might not have thought of:

  • Lighting confuses migratory birds. Millions crash into buildings every year.
  • Sea turtle hatchlings walk towards city lights rather than the ocean.
  • For us humans? An increased likelihood of breast cancer among women who work at night.
  • Depression and sleep problems.

Worst may be the lack of perspective we humans get when we can’t contemplate the vastness of space. One of the astronomers in the documentary noted that when we lose touch with the scale of the universe we don’t appreciate the fact that we will never leave this earth. The distances are just too great. His point is that if we understood the impossibility of space travel, and gave up fantasizing about space colonies, we’d take better care of our home.

Photo: highline.org.

Highline Park at night. Photo: highline.org.

Keeping Gardens Dark
Thankfully light pollution is an easy fix and saves money and energy too. We can keep our outdoor spaces dark at night to benefit our well being and as well as the survival of nocturnal creatures. Night Sky concluded with a brief interview with Hervé Descottes, one of the lighting designers of the Highline Park in New York City. Descottes’s lighting design shows how you can balance the need for security with respect of the night sky by simply directing lighting downwards.

The International Dark-Sky Association has a guide to residential lighting that will help you keep our skies dark and nocturnal creatures safe. Some recommendations:

  • Choose dark sky friendly lighting fixtures that direct light down, not up.
  • Light only what needs to be lit, i.e. create a lighting plan rather than putting up a huge floodlight.
  • Switch lights off when not in use.
  • Reduce wattage–you don’t need as much as you think.

Here’s another idea: garden with moonlight. Rather than light up your garden with artificial light, include plants with silvery-grey leaves or white flowers. Our white sage glows spectacularly during a full moon. I’m also happy we put in a climbing white rose over our entrance arbor.

By embracing the darkness we can open our eyes to the stars above.

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19 Comments

  1. In Florida, if you live on the shore, it is against the law, with high fines, to have outdoor lights facing the beach. Obviously this is to protect hatching sea turtles. I think it even applies to using flashlights to watch the hatchlings.

    Solar lighting for the garden is very popular and does promote low level light that is projected downward. I never understood why anyone would want to have those garden spotlights on their trees at night – who’s out there to see it?

    If you want security lights, make them the motion detector type – they work well, are on for a very short period and do not disrupt plant life nor annoy the neighbors all night.

  2. Thank you for this. Makes me excited for warmer weather and an opportunity to be outside at night, enjoying the starts. Although I wish my neighbor would get a clue and tone down the floodlights/spotlights illuminating his backyard continuously each night, and by proxy, my yard. Who doesn’t know you can make the lights motion-sensored?

  3. The Dark Sky Association also has a study critiquing the idea that lighting prevents crime.

    It turns out criminals like to see who they are attacking. The don’t want to jump somebody in the dark, only to find out they are a linebacker fresh from judo practice.

  4. When I was a child in the 40s and 50s, Mama and Daddy would take a quilt into the yard and we would lie on our backs and look at the stars, constellations, and the Milky Way. And, we lived in Memphis, a fairly large city even then. Now, in my tiny town, there is no way I can find stars many nights, much less see the Milky Way.

    I have always held this unfounded notion that plants need the dark to grow better and have a cycle of light and dark. A friend told me her husband said a tree lit all night where he worked never was as healthy as the other trees with no direct light on them. Of course, there could be other factors at work.

    During our ten days of no light after a tornado tore up our town, the crime rate was very low. Only in the immediate aftermath did people loot, and then only the gun shop. Of course, the next ten nights, there was a curfew and the National Guard enforced it strictly. AND, none of the stores were open after dusk. So, I am not sure of the reasons for low crime statistics.

  5. Preach it! I keep light out of my backyard except for a motion light at the back door. Unfortunately, my county installed new LED street lights, and they reflect off neighbors’ windows into my yard. So annoying, especially in concert with the neighbor’s bright backyard lights. I just don’t get this mindset.

  6. “that you can count the number of stars in the night sky.”……..is it that you cannot count the stars in the night sky?

    • I should have phrased that better–here in the middle of Los Angeles you can count the number of stars in the sky and the total is around 12 or 20 on a good night. You can’t see the milky way, of course.

  7. Thanks for posting this! It’s been something I rant about all the time. My father was an astronomer and I can’t stand it if the sky is light enough that I can’t see the Milky Way, and that’s not very light!

  8. I hope you never stopped being an astronomy geek! Next time you’re in the bay area, consider yourself invited to an event hosted by the San Jose Astronomical Association.
    http://www.sjaa.net/

    We’re always having to fight for our little spot of darkness in the city, but we are also constantly scouting out darker sites a little further away.

    Thanks for the plug on keeping the night sky dark!

    • Hey Rob–I’d love to visit you folks. I actually still own my childhood telescope–a Dopsonian. I’m considering getting it working again and having some neighborhood star parties.

  9. Dobsonians give the best bang for your telescope buck, good for you. I encourage you to dust it off, get it outside and share the views of the night sky. Even in light polluted areas, you can still see amazing stuff. Right now, Jupiter’s in a good spot in the evening.

    I’m sure you’ve heard of guerrilla gardening. I’m an advocate of guerrilla astronomy, in the spirit of John Dobson, who invented and open sourced that Dob design we all know and love. He did the sidewalk astronomy thing starting back in the 70s or so. And as you may have heard, we lost him earlier this year, but he had a long, great and impactful life.

    If you want tips and pointers on hosting a good star party, email me, and I’ll point you to some sources. Good luck!

    • I should have added that it’s a 13 inch first generation Dobsonian–painted a vibrant speckled blue! It works great even in Los Angeles. I may need to have the mirror re-aluminized.

      Would love to have some star party tips. I used to take the scope up to public astronomy days at the Griffith Observatory. People were thrilled to look through it. And I once ran into John Dobson at a beach in San Diego–I have great respect for what he did.

    • Here is a good HowTo run a star party, from the Astronomical Association of Northern California:
      https://sites.google.com/site/aancsite/articles/host-a-starparty

      And from the same AANC site, Jane Houston Jones (who moved from the bay area down to the LA area a while ago) wrote about hosting a school star party, much of which is applicable.
      https://sites.google.com/site/aancsite/articles/schoolstarparties

      Good luck, and I hope this gives you the encouragement to do it! Let me know how it goes!

    • Many thanks for this info. I can’t wait to get my telescope operational again and share the sky with people. There’s a local school garden where I think the star party idea would be very popular. Since your comments I’ve been thinking about how important this is–to get people to look up at the night sky again. I realized that I’ve become really detached from the night sky since I stopped doing astronomy. Will fix that soon. Thanks for the inspiration. Hope to meet you in person someday–I’m up in the bay area a couple of times a year.

    • It would be great to meet up. Not sure exactly where you are, but I’ll be in Oceanside next week. But I think that’s too far south of you, so be sure to ping next time you’re up north. And good luck, report back how it goes!
      Rob

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