measuring light levels.

[samarak]

Originally Posted by Ray

Small shafts of direct sunlight are not an issue, as they do not stay located on a single part of the plant - as the earth rotates, the spots "move", avoiding overheating of the tissues.

Be careful about AOS culture sheet light levels, as the numbers are recommended peak intensity levels seen in a day, and not the intensity it should see for the whole day. For windowsill and greenhouse growers, that's fine, but sometimes folks growing under lights "overdose" their plants by doing just that.

We have actually changed our shade cloth arrangement in the greenhouse this year to narrower strips with a deliberate gap of just a couple of inches which allows a few very narrow bands of more intense light to move across the benches during the day. I have absolutely no scientific evidence to support saying that the plants like it, since there is no rigor and no control group, but our unscientific impression so far is that they do.

Steve

[Ray]

As the light absorbed can be considered to be a "mass" of photons, I doubt that a shade cloth allowing "X"% of the light to pass is no different than lath slats that allowed the same percentage to pass.

Of course, I suppose that 100% of 50% shade is different from 50% of 0% and 50% of 100%, as the unshaded "bands" would probably cause some heating of the plant tissues, increasing the metabolic rate.

[bil]

Originally Posted by Ray

Small shafts of direct sunlight are not an issue, as they do not stay located on a single part of the plant - as the earth rotates, the spots "move", avoiding overheating of the tissues.

Be careful about AOS culture sheet light levels, as the numbers are recommended peak intensity levels seen in a day, and not the intensity it should see for the whole day. For windowsill and greenhouse growers, that's fine, but sometimes folks growing under lights "overdose" their plants by doing just that.

Thanks Ray. I'm hard out to find an ideal location. A bit like Goldilocks, but without the nice solution.. The sun has a nasty reach, with some places getting massive illumination just when not needed, or else not enough.. the best places are either hit with too much light at midday, or else the area is plunged into complete shade for half the day.

Ah well, I shall just have to keep searching.

[james mickelso]

And that is the conundrum. Orchid light levels are not exact. From species to species, and within any species, the requirements change. I think you are looking for too much. As long as the light isn't scorching the leaves the light levels within any range will be sufficient. I wouldn't read too much into it. There is no perfect, or even close.

[samarak]

Originally Posted by Ray

As the light absorbed can be considered to be a "mass" of photons, I doubt that a shade cloth allowing "X"% of the light to pass is no different than lath slats that allowed the same percentage to pass.

Of course, I suppose that 100% of 50% shade is different from 50% of 0% and 50% of 100%, as the unshaded "bands" would probably cause some heating of the plant tissues, increasing the metabolic rate.

I was indeed after something like the effect of lath slats, Ray.

At the risk of wandering off into the technical, I'm not terribly religious any more about instantaneous light intensity readings, other than to avoid damaging the plants. My questions are more about the range of the values through the day and what the agri folks call the daily light integral (the area under the intensity curve) which of course does treat the photons as an accumulating mass.

Steve

[bil]

Interesting. From a lot of personal observations with animals I have noticed that the closer you can get to what they experience in the wild, the better they do in captivity. It appears very plausible that a dappled shade would be better than a constant light level, if that is what those plants have evolved in.