How many hours do I leave the Lights on..?
 

Now that I have (2) CFL fixtures with 6500k spiral bulbs in each fixture, I'm wondering how many hours do I keep the lights on ....?

I've been turning the lights on when I get up and leave them on all day .... depending on how I turn the fixtures I can get between 1500fc to 4000fc of light on my orchids.

I keep mine on for 12 hrs in winter and gradually ramp it up to 14 for summer. In late Sept. I'll gradually go back down to 12. Tindo is right though. Most tropical plants are from around the equator and experience 12 hrs. of daylight all year long.
By the way, put them on a timer. Then you don't have to worry about it.

Bill

I would second the timer idea for reasons of expedience as well as consistency. There are some orchids that don't appreciate any significant variance in their light cycles.
I typically run my lights 12 hours per day throughout the year.

For my tropicals (all seventy some odd of them), I keep the light somewhat similar to what's going on outside during the winter. There is one overhead light though that is not on a timer, and I turn it on and off by hand. That one I will turn on when I wake up, about 1 hour before "daylight" in the growing area and then I tend to leave it on for an hour or longer after "daylight" has stopped in the grow area. For me, this helps the plants that need more light. I kind of see it as the sunrise and sunset period where they are getting light, but just not as strong.

I have no scientific verification if I'm doing this right, it's just by feel and it has worked for years.

That being said, I only have a few orchids in my grow area. The rest of them are in windowsills throughout the house and get the light naturally. They all have done fine on the "natural light" schedule. Again, it depends what kinds you have as to what their needs are though.

I do the same thing. I have all of my lights on timers and I set them to turn on 1 hour before sunrise and 1 hour after sunset. This way the daylight period "adjusts" for the seasons. If the daylight period is going to be less than 12 hours, I set it for 12 hours, regardless of sunrise and sunset. I have no scientific proof, but I feel like the shorter daylight periods (together with a drop in temp) helps the phals and paphs spike.

-J

Looks like I need to change the setting on my timer. I keep mine on for around 16 hours. The plants seem to do okay. Plenty of new growth and flower spikes are fairly regular, I assume. I am still new to this so flowering times are still a little hazy to me.

Sixteen hours should not be a problem, Amanda. I run mine from 12-16 hours (less in the winter). I don't know if the change really helps, but do know that a lot of plants are daylight sensitive. I've seen articles advocating up to 18 hours of light.

Would the 16 - 18 hours of usage be needed because the wavelength from the bulbs is not as good as natural daylight wavelength?

Mine are 12 hour and I might increase that to 14 in the summer, but that is about it. Plants need to have time for darkness functions...follow nature. What happens there, we should do the same.

No, from what I've been told this is a myth.

I keep my lights on 14 hours in summer, 12 hours in spring and fall, and 10 hours in winter. They all bloom and grow well this way and ''know'' their schedules.

Careful studies in non-orchid plants show that it is the total photon flux that a plant receives that is important. There is a maximum amount of light a plant can use and anything beyond that is not a positive. So, an under lights grower would lengthen the light exposure to make up for a reduction in illumination, if that is happening. We can't go by foot candles/lumens measurements exclusively because it depends on the wavelength distribution of the lights.

With my LED lighting situation, known wavelengths of the light, and measured foot candles I am using 17 hour days for most of the year to equal what would happen in a well positioned greenhouse in my Northern area that limits maximum illumination to 1,500 foot candles with the use of shading.

Do you leave the lights on 7 days a week, or do you leave them off one or more days a week? I have my timers set for 10 hours winter and slowly ramp them up to 16 hours summer. But I was wondering if running them everyday puts stress on the orchids. In the wild there are rainy and cloudy days after all. Any opinions?

Mine come on at 5 am and go off at 9 pm

I have a slight variation on what everyone has already reported....it is cheaper to run my lights after 7pm. So since I grow in the basement with no sunlight, mine come on at 9pm and run for 11 hours for winter. I will slowly adjust the time near spring to be longer and turn on later as the seasonal electric rates change. No idea how much money it saves but because the boiler that heats our house is in the basement too, it is running a lot during the coldest part of the day which is night, so the basement enjoys a warm up when the lights come on. Coincidence and I don't know if the plants care but it seems more natural for them.


Ryan

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Contrary to what you've been told, Orchid Boy, that is NOT a myth. There is nothing in the man made world of lights that can compare to the sun. Yes, the sunlight varies at times of the day and seasonal and blockage by weather and clouds and trees BUT it's still the BEST light ever. Between the consistency and lengthening the duration of our lighting it comes as close as we can get to real sunlight. Without either of those it's like comparing a bucket of water to a lake !

Mine are on a timer 12hrs/day, 7 days/week and 15 hrs/day during daylight savings.

I found this website to be a great source to find out how long to keep the lights on during different times of the year. It goes by which latitude you live on.


Day Length

Yes, orchids from equatorial regions get 12 hours of daylight - but bear in mind that's not all full daylight. There is dawn, sunrise, dusk, and sunset in nature, when the light is not as strong and comes from a lower angle. Artificial lighting sources typically blast their light down on the plants with no variation in strength for the whole time they're on. Under bulbs, the total light the plants receive is far more than they'd get in nature. Thus, I like to go down to 10 or 11 hours in winter, up to 14 or so in summer. -Stephen

I would only add that it all depends on the intensity of the light that you can deliver with artificial lighting. The weaker your intensity, or the more suboptimal your light spectrum, the longer your day length needs to be to compensate. Obviously, this applies to a greater degree to higher light requiring orchids. There are published data on the illumination at a spot throughout the day, showing the large variation, so you can even calculate how many hours of steady illumination with different intensity lights you need in order to match the total photon flux (or foot-candle hours if you wish) from the natural light.