Hours of Supplemental Light?

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Wow! Loaded question and a good one! Depends on the light intensity, temperature, air movement, watering, plant in question (of course we're assuming slippers, but certainly some need more light than others ex philippinense vs Maudiae-type hybrids)... Another way of saying 'I don't know for sure'. *Theoretically*, plants need a certain number of photons per day, and, as long as they get that, they *should* grow and bloom fine as long as they're not daylength sensitive. For instance, we can bloom standard cattleyas under four T12, 40 watt fluorescent tubes (leaves just short of touching the bulbs), but we have to use a 16-18 h daylength to get them the light (ie. number of photons) they'd get in a typical day in the tropics. But it's darn unnatural to give Paphs a couple hours of 'on the sun' bright light then turn the lights off the rest of the day. Your ability to keep the leaves from burning and to keep the plants properly hydrated and with sufficient nutrition during the on time would be crucial. A perfect question for Yin-Tung Wang. What's your goal Heather?

Actually, its a perfect question for the Magic 8-ball. :poke:
Stop being so cheap. If it's really necessary don't run the lights at all. The plants will survive they just might not bloom as well.
I don't think most paphs are light sensitive in the way you are concerned about (long day, short day floral initiation). Or if they are I've never heard it (or saw it when growing only under lights).

Heather, I think if you are concerned about short days (they are getting longer...), it would be best to start with just extending the days a bit. I think 12 hours is a good starting point, just have your lights on (at the beginning or end of the day) for however long it takes to approximately hit that. In the summer, turn them off. However, I would focus on one end of the day, turning lights on and off is hard on the ballasts. Once a day cycle is going to let your lights live longer than twice a day.

And yes, I will eventually send that light rail to you. Eventually... :arrr:
I think that since many of our tropical plants kept inside still cue in to some kind of season for blooming its probably more related to light (and daylength) than temperature fluctuations.

Although we assume that plants close to the equator will always be on a 12 hour shedule, the effects of cloud cover during seasonal monsoons act like shorter days.

I'd go for 14-16 hours during the summer, and 12 in winter for indoor lighting systems. As Ernie said the intensity can have allot to do with it.
No, slippers aren't day length sensitive (to my knowledge). But several Cattleya species are. Was just making a point- tried to stretch it beyond the slipper realm. We usually go for 14-16 hour days for the slippers. Again, the key is that when you screw with light, you don't just screw with light- all factors of culture are closely knit.

This is mostly a mission to get my electric bill down a little.
Because I don't really get any natural sunlight right now, I thought about possibly switching to an off peak schedule. The problem with that is, though there is no sunlight coming in the windows, it is daylight and I don't have blinds, so would it be dark enough during the day for the plants to have the difference they need?

If not, then my thought was just to not run the lights until I get home from work around 5, and then run them for 6-8 hours overnight to give them the extra they need. With that method, when the sun changes it's angle in the next month or so I will be getting some good sunlight during the day and could potentially back down on the number of hours.

Any thoughts?
Hi Heather,

I've been growing under lights for years, and I follow a 12 hours in winter / 16 hours in summer schedule. I'm inclined to think that a plant's metabolism is co-ordinated not only with daylength but with corresponding changes in temperature and possibly even relative humidity. I think it is best to follow nature's example.

What does your collection cost you in turms of energy costs? Have you considered more energy-efficient lamps and ballasts?

If you do make a change, Ill be very interested in hearing about the results.

Thanks Rick,

I have a strange mix of lighting across a ledge that is about 10 feet long. I have a 400W MH that sits above my roth/philippinese/kolapakingii crosses in the middle (no window there). Seedlings and slightly lower light level plants are further out from those lights, but in front of two south facing windows. So, those plants get the residual from the MH and sunlight (more in summer than winter, south facing). On the far ends, I had clamped 2 160W wonderlite fixtures. Unfortunately, the fixtures fail miserably. I had three, two were replaced under warranty, but now they are out of warranty and one failed last week, I am afraid the last may go soon. So, I have replaced the failed wonderlight with a clamp on 150W compact fluorescent.

I also have a cart where I use four additional 150W compact fluorescent fixtures above my Phrags. They grow and bloom well under them. The cart will get some sunlight as we move towards summer.

That's downstairs. :)
On my stairway going upstairs, I have another ledge and another window and one more compact flourescent over my Mexipedium. Again, grows well there.

Upstairs, I have three north facing windwos and a south facing (sorta) skylight. The light from the skylight hits one more tray of plants (the kolopakingii hybrids that won't fit downstairs. Compact fluor. over them.

So, the total right now is:
1 MH (400W)
1 "wonder"light (160W)
8 compact fluors. (150W each)

I had been running 6AM to 7PM but they are waking me up too early, so that was why I started thinking about these different schedules. Currently I have them 8AM to 11PM but that's likely going to run up the electric bill a bit.

My electric has been about $140 a month. I'd love it if it was closer to $100. It wasn't really an issue until it got cold this month and I had to turn on the heat.

Other than the orchid lights, I RARELY turn on anything else. I don't use my large oven (electric), mostly use a small convection toaster oven. I don't use my upstairs heat (electric, downstairs is gas). If it's dark, I will use a small lamp w/ a 40W bulb, but now that the lights are based on my sleeping schedule that should quit also. The only other drain on the electricity is my washer and dryer. My dryer is pathetic and it takes an extremely long time to dry anything in it.

I definitely don't want to screw up the plants, especially since the seem to finally have recovered from all my moves (3) last year. I just wonder if there is a bit more economical way to grow them.

Here's a couple of old photos after my last move. Lights weren't up yet but it gives you a visual. And this was when there was sun coming in the windows. :) This was also before I moved the Phrags onto the cart.


Most residential electric meters do not include a clock, and time stamp. The result is whether you use a kilowatt during peak hours or off peak hours you pay the same. Ifyour electric bill DOES have separate charges for peak and off peak uses, then you can shhift your use to cut costs. You can just run your lights at night (off peak) if this is the case. Otherwise, shifting your time of running the lights won't matter.
If you are only talking about disrupting the light schedule for a month it probably does not matter how you do it, your plants would be OK.
But if you are looking for a long term solution to reducing the electric costs your only satisfactory solution is to reduce the number of lights you have, which means to reduce the number of plants you have also.

If you don't give your plants their optimum day length and light strength over time they will begin to decline. You won't be happy. If you need to reduce your expenses you will be better off making your collection smaller. What's the point in having the plants unless they are growing well? Weaken the plants and you open the door for ill effects in the future.

Remember, plants have a memory and know when sunset and sunrise is going to happen. In nature if the sun comes on at 6:00 it will come on at near 6:00 tomorrow. A plant knows this and at say 4:00 it begins to change it's internal process and prepares it's metabolism to use the sunlight. A rhythm develops and plants grow well. Break this rhythm by having daytime come irregularly and you mess up the plants internal functions and good growth stops. It takes some time for the plant to shift gears from light to dark so breaking up the light hours becomes very inefficient for the plant.

You may find that when a plant has been all day in very low light levels and then suddenly gets bright light it may take several hours for the plant to shift gears to begin efficient use of the light. So you may not even get the full value from the 6 or 8 hours of light you are considering using in the evening.
gonewild said:
If you are only talking about disrupting the light schedule for a month it probably does not matter how you do it, your plants would be OK.
But if you are looking for a long term solution to reducing the electric costs your only satisfactory solution is to reduce the number of lights you have, which means to reduce the number of plants you have also.

I know, which is why I am trying to sell off a bunch of plants. :)

Getting a light rail would help, but I think I would still need two lights on the end, at least during the winter. Once the plants I have sold are gone, I am hoping I can fit the three that are upstairs down here, which will eliminate two lights.

I guess I'll keep it on sunrise - 9pm for now and see how things go.
Thanks for all the thoughts on this, I really apprecate it!
How many hours of natural daylight do you have now?

Maybe there is a method to maintain your plants at given point for a while while you stabilize your finances...... Find a point of light where the plants don't necessarily grow but they also don't suffer either

If you did decide to use your lights for a shorter duration to save money you might try running the lights in the middle of the natural light period.
So you end up with dark turning to a few hours of low level light simulating early morning and then bright light for mid day and then several hours of low light level simulating late afternoon and then back to dark.

Just another idea.
Heather, I truly sympathize with your lighting issue. As I have full southern exposure, my plants get almost too much light and the temp rises to about 80 everyday. I recommend you send all your Phrag besseaes and the hybrids to a better condition [my house] and take up growing truffles and hitakes. :rollhappy:
PS. since the electricity is included in our [controlled income] monthly maintenance I can run lights, at no additional cost, to my heart's content.

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