Light Questions - What Exactly do the recommendations mean?

[LobsterOfJustice]

Hi,
What exactly do the recommendations for light mean?

For example, the AOS recommends that phals get 1,000-1,500 foot candles.

Does this mean they need an average of 1,000-1,500? So the way the light may actually break down would be like 500 foot candles for 2 hours, then 1,000 foot candles for a total of 5 hours, then 1500 foot candles for 3 hours, and 3,000 foot candles for the remaining 2 hours, which provides an average of 1,250 foot candles for the day, which is within the 1,000-1,500 recommendation.

OR

Is the recommendation the min/max light? Which would mean that phals need somewhere between 1,000 foot candles and 1,500 foot candles all day, so the breakdown of light above wouldn't work because there would be a few hours where the light isn't strong enough, and a few hours where the light is too strong.


Also, what does the max mean? I saw somewhere that the max for a phal is around 3,000 foot candles. Does this mean that anything more than 3,000 foot candles will cause sunburn/sun damage on the plant, no matter how long the plant is exposed to that light?

OR

Does this mean that 3,000 is the max average that the plant should receive? Meaning the plant can actually have much higher than 3,000 foot candles as long as it's not sustained for long, so for example, 30 minutes at 6,000 foot candles would be OK as long as it's no longer than that and the average for the day doesn't go above 3,000?

I have a light meter and am trying to make sense of the readings I'm getting. In mid-day sun, my phals might get 3,500 foot candles, but only for 2-3 hours, and for the rest of the day, it varies between 100 and 2000.

[Leafmite]

One thing to remember is that, when you are talking about light for plants, you must also consider temperature, humidity and air-movement. This can be different, too, for different plants. The best way to understand what light your plants need is to try to learn about the environment from which they derive. Cloud forests have different conditions than a savanna...yet orchids come from both environments and might, in their native environment, have equal exposure to light.

[terryros]

The recommendations reflect the peak light that the type of orchid receives during a typical day in natural light conditions. For under light growers, you only need to provide about half of this intensity through out the day's light period to approximate the total amount of light the orchid needs. Ray Barkalow has nicely shown this with simple geometry in several other posts.

The type of light you use, and maybe even how directional the light is, will influence how intense the light falling on the plant needs to be.


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[cjm3fl]

Duration is another consideration.
I grow outside but my Phal's begin setting blooms during the part of the year with the fewest hours of daylight (Jan and Feb).

Some commercial growers "trick" plants into bloom by adjusting the duration, as well as intensity, of the lighting.

Sorry. I know it's something else that just adds to the confusion.

[estación seca]

The footcandle measurement is most useful to people growing under lights. People growing in natural light often keep moving plants into brighter and brighter conditions until the leaves begin to get a little yellow.

[Ray]

Originally Posted by cjm3fl

Duration is another consideration.

I grow outside but my Phal's begin setting blooms during the part of the year with the fewest hours of daylight (Jan and Feb).



Some commercial growers "trick" plants into bloom by adjusting the duration, as well as intensity, of the lighting.



Sorry. I know it's something else that just adds to the confusion.

Phalaenopsis do not respond to changes in day length, they respond to a period of decreased temperature. After they have experienced that - commonly happening in the autumn, after a hot summer - it takes time for the spike to mature and bloom, making the plants "winter bloomers". The shortest days is just coincidence.