24 hour photo period?

[Brotherly Monkey]

I was wondering if anyone ever tried treating their orchids to a continuous light cycle, and if so, what type of results did you see?

[jkofferdahl]

You'll likely see the plants perish. Plants, like people, need a rest period.

[marydaniellesantos]

I agree with jkofferdah. LOL. You should at most mimic the suns patterns.

[RosieC]

I know some people have managed to switch night and day successfully for plants that get natural light, but not 24 hours a day.

I agree with John, I believe they need a dark rest period daily.

[johnblagg]

I have ocassionally done this throuhout this last winter .....I did some playing around with the light schedual for my catts ....

I used a month of long days and then three or four 24 hour days and then back to a short day cycle for about a month and repeated the cycle ...I got really good growth throught the winter and three sets new leads two of which are mature and the last set is taking forever since I went to the same schedual as natural for the summer ...

I plan on trying the same this winter when short days will allow me to manipulate the lighting again to my liking.It is just not possible during the long summer days to go to short day lenght without a special room which I do not have

Actually it is usually the lenght of the dark period that is the actual trigger and the day lenght can be made extreamly long as long as you can give a dark period in between ....sy 24 hrs light and 13 dark but it gives very odd times for lights to be on or off

The plants still need the dark cycle especially plants like orchids that do their actual transpiration during the dark cycle so you can not eleminate it for too long with out causing more harm than good

[Brotherly Monkey]

Originally Posted by marydaniellesantos

I agree with jkofferdah. LOL. You should at most mimic the suns patterns.

Meh, I don't buy into the "mimic nature" argument. I mean, in nature, plants don't grow in my basement under artificial lights, right?

[Undergrounder]

Originally Posted by Brotherly Monkey

Meh, I don't buy into the "mimic nature" argument. I mean, in nature, plants don't grow in my basement under artificial lights, right?

Completely agree. There's no a priori reason why you can't give orchids continuous light. Two important points though..

1. I believe the only major factor to consider is the orchid's respiration cycle. A 24/7 light cycle shouldn't be a problem for C3 orchids, (mostly the thin-leaved types like Cymbidiums, Oncidiums, most Paphs). They have stomata that open during the day, and are able to photosynthesise (and grow) without requiring a dark period.

But the CAM orchids (like Phalaenopsis, Cattleyas, Dendrobiums, Bulbophyllum...) require a dark period for part of their cycle. Darkness (or absence of light) stimulates the orchid to open its stomata and gather CO2 from the atmosphere. This is stored in the form of Malic acid, which builds up in the cells of the plant.

During the day, the malic acid is decarboxylated back into CO2 for use in photosynthesis, where it is combined with oxygen and water to create sugars used in growth. Without the dark period, the plant would not be able to gather the essential CO2 used to grow.

So this is the problem for CAM orchids, But even for the C3 types...

2. Just adding more light (either through intensity or length of day) won't help unless you also increase the other major limiting factors on growth (light, water, food and CO2).

WATER is the most pressing limiting factor for growing epiphytes (and generally not light). So if you increase the light period (or intensity), you won't get better growth unless you give it a lot more water. But that's OK, let's assume you use a semi-hydroponic system and can address that need. And let's say you can feed them regularly with fertilisers, so that takes care of that.

CO2 is the next most pressing limiting factor in epiphyte growth, and this is the real problem. If you increase light AND water AND food, you also need to give it more CO2. You can do this with a CO2 tank and bump the levels up to a max of about 1500ppm (air is only 300ppm CO2), at which point the plant hits another limiting factor: The sizes of the holes in the leaves through which the CO2 flows (the stomata). More than 1500ppm is ineffective and detrimental to growth in orchids, and only so much can flow into the plant anyway.

And this is a roadblock you can't overcome. Limits on CO2 uptake will always limit growth, where extra light will just be ineffective and possibly stressful on the plant.

So my point is 1. Most orchids require dark periods for respiration. 2. Even in the orchids that don't require a dark period, there is no benefit to having the lights on 24/7 anyway... you could probably get the same growth with brighter intensity lights and an ordinary photoperiod.

[marydaniellesantos]

It was just an idea, and I was only talking from my own experience, my orchids have been doing great with 12 hours of light. I hope everything works out though! Let me know what you find out! It may be worth changing up a bit.

[Brotherly Monkey]

Originally Posted by Undergrounder

But the CAM orchids (like Phalaenopsis, Cattleyas, Dendrobiums, Bulbophyllum...) require a dark period for part of their cycle. Darkness (or absence of light) stimulates the orchid to open its stomata and gather CO2 from the atmosphere. This is stored in the form of Malic acid, which builds up in the cells of the plant.

certainly little you can do about the above

Originally Posted by Undergrounder

CO2 is the next most pressing limiting factor in epiphyte growth, and this is the real problem. If you increase light AND water AND food, you also need to give it more CO2. You can do this with a CO2 tank and bump the levels up to a max of about 1500ppm (air is only 300ppm CO2), at which point the plant hits another limiting factor: The sizes of the holes in the leaves through which the CO2 flows (the stomata). More than 1500ppm is ineffective and detrimental to growth in orchids, and only so much can flow into the plant anyway.

couldn't this be dealt with through adequate ventilation?

[Brotherly Monkey]

Originally Posted by marydaniellesantos

It was just an idea, and I was only talking from my own experience, my orchids have been doing great with 12 hours of light. I hope everything works out though! Let me know what you find out! It may be worth changing up a bit.

No worries and I really appreciate any and all input. I just there is really little reason to limit yourself by "what's in nature" when you are already growing in such an artificial environment.