Beware--Street and Porch Lights

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
May 25, 2005
Reaction score
Because I know a lot about growing pot, I am sometimes asked to "trouble-shoot" a friends pot garden.
A backyard pot garden is the bomb. So easy to tend, so easy to observe.
But there can be problems.
One time a friend called and asked me to come over and see if I could figure out why their outdoor plants weren't budding.
As I walked into their backyard, I saw the problem right away.
Though behind a 6' high wall, a nearby streetlight was in line-of-sight with the plants.
To flower, plants need 12 hours of uninterrupted darkness every 24.
They weren't getting it.
The person assumed that since the street light didn't seem any brighter than moonlight, it wouldn't affect the plants.
She was wrong.

Most people think moonlight is brighter than it actually is. And the wavelength of light from the moon is different than light from a streetlight.

We rigged up a canopy out of a tarp and some sticks and that solved that problem.

Another time, it took me a bit longer to figure out.
I went over at night. There were no nearby streetlights. I asked if they were going out at night with a flashlight to look at their plants.
"No, we never go out the back door at night except to put stuff in the trash cans".
Aha! I looked and saw the back porch light. Bingo!
That problem was more easily resolved--just unscrew the bulb, and empty trash before dark.

It doesn't take much light to prevent budding. Another friend had a problem with his closet grow. I scoped it out and found the problem. The little red light on the power strip in the closet. That problem was resolved by a tiny piece of black tape.

If you're the type of person that absolutely MUST look at their pot plants during the dark cycle, you can use green light. The plants don't "see" green light.
Some people say a green lens over a regular flashlight is safe. I don't know about that.
But there are 2 sources of green light I KNOW are safe to use.
One is those "break and shake" lights--those sticks that kids use for trick-or-treating. Keep one handy.
Another way is to use a green l.e.d. keychain flashlight. You can get these at gas stations/auto parts stores etc. They're cheap, Campmor sells them for 5 bux.

P.S. Someone I read about tried to solve their streetlight problem with a BB gun. It put out the light alright.
But a few days later a city crew came out to replace the light and guess what they noticed? The crew notified the cops and the person was busted for cultivation.
Would the headlights of my car coming down my driveway at night affect the cycle. The plants would get hit with light from my headlights for 30 or 40 seconds if coming home at night.
One more question, if the plants dont have direct line of site would the light from a flood lamp affect them from 75 feet away?
I had a problem with the sensor light in my backyard last season.(neighborhood cats!!) Once I figured out that's what was preventing them from flipping I threw a tarp over the small greenhouse that they were in. Once they started to flower the sensor light didn't bother them but it was preventing them from starting.
Ive been growing outside for years now and have yet seen where the "Street" lights..."porch" light have an effect on flowering. Hell my neighbor use the street light for his back yard and never had issues...

Next would be the "Moon" Light
i once flowered plants in a spot that gets light from buildings 100 feet away, they just flowered with no ill effects
i once flowered plants in a spot that gets light from buildings 100 feet away, they just flowered with no ill effects

yeah i got two nearby streetlights, and a busy neighbor (always has his yard light on - off)
don't have a problem.

i think you'll be fine buddy, as long as that flood light aint pointing straight at them.
I have a buddy with the same problem. He and I would start our gardens at the same time, but his were always behind mine. I observed his garden one night and noticed his porch lights and his streetlights were providing too much ambient light. I told him this and he blew me off. He has his plants in containers and I advised him to move them to a very dark spot to sleep. He is too lazy and his yield is always much smaller than mine.

Another grower had a very bright porch light and his plants did not flower until December! LoL

Latest posts