Lighting question (how long at exposure)

[jay]

Hello,

I have found lots of info about how much light different types of orchids should have, but I have not found for how long they should remain at that level.

I have a 4 tier wire shelf for my orchids. It faces an East sliding glass door/window. Unfortunatly, the window in tinted (I live in the desert, and this is needed).

I have just purchaced a light meter to find out how much light they are actually getting. And here are the results. Keep in mind that this will be close year round as we have about 350 days a year without any clouds.

Beginning around 6 am, the light starts at about 2000 footcandles. This is through the window (outside direct is about 8000 fc). The top tier will fall into shade and drop to about 300-400 fc by 9 am. By this time the bottom 3 shelves are now getting about 3000 - 3200 fc of light. About every hour another tier will fall into shade until about 11am, at which point all four levels are getting around 350 fc. I used to think that this room was bright. Wow, what a surprise.

Even though the direct light is about 10k -12k fc in afternoon, the tint really takes it out. Is this tint also "killing" certain spectrums of light needed? Will it filter out what is needed?

Is this long enough at the higher light levels, or will they need supplemental light after they fall into shade?


Humdity is always an issue, but that is for another post.


Any thoughts, comments, or tips would be greatly appreciated.

Thanks

Jay

[kmarch]

Hello Jay and welcome to the forum!

I wouldn't think you need to do anything to further control the amount of light you get. In your east window you'll be able to bloom pretty much anything (Cattleyas, Phals, Paphs, Oncidiums, Vandas, Coelogyne, Phrags, and all of their relatives). In my opinion you don't need supplimental lighting or shades.

What are you growing? How long have you been growing this way? Have your plants been growing and blooming?

[jay]

This shelf is new, but I recieved my first Phal about 2 years ago. It bloomed several times before I moved and could not take it with me. I now have aquired mostly through gifts, a 3 oncidiums (intergeneric hybrids), 2 cattleya (again unknown), 1 phal.

I just wanted to make sure that they were getting the intensity of light needed for a long enough period of time because for most of the day they only get about 350 fc of light.


I have had two of the oncidiums re-flower in this area. My next biggest problem is hydration. All of the pseudobulbs tend to wrinkle. Does not appear to rotten roots, but afraid to overwater.


Thanks for the thoughts,

Jay

[kmarch]

Jay,

I'd stick the Cattleyas and Oncidiums on the part of the shelf closest to the window and keep the Phals back on the part of the shelf furtherest form the window.

I little wrinkling of bulbs is probably nothing to worry about, but the low humidity may require more frequent watering (see my comments in yoru humidity thread).

Regarding the 350 reading on the light meter: I dont' put much stock in light meters. I have never used them and have, for more than 10 years now, gone by "high" "Medium," and "low" light designations. I seem to recall another forum member havign light meter readings thrown way off by some sort of glazing on the window yet her orchids performed as they should eventhough the light meter said they were getting somethign like 10% of the amount of light they should have received. i would go by the plants' performance not a light meter reading.

Keep us posted on yoru progress!

Cheers

[Vivienne]

That would be me Kevin. I have all my orchids in an atrium with 3 large skylights. The skylights are tinted and cause the light meter readings to be ridiculous... 2000fc in the direct path of the sun and 100fc just 2 inches past the direct path. I have a large assortment of plants from paphs to cattleya. All of them are doing just fine. All that said... my opinion is that the tinting is allowing in the proper light levels that my plants need and still keeping the burning light level out.

Not all tinting is the same though, so keep an eye on your plants until you get the feel.

[jay]

Thanks for all the tips. I always thought this room was bright, it also has some windows along the cathedral ceiling to allow even more light in. That light is never in direct contact with the plants though.

I will let you know as time progresses on how the plants do with this light.

thanks


Jay

[Anton]

Lightmeters are a rough guide only and not to be taken as gospel.

They give you a number for the intensity of light in an area where your plants are and there are variables and a reasonable range in which the plants will tolerate light intensity differences.

I am like Kevin and look at light intensity and put an intensity on that light eg bright sun, sunny/shade, bright shade, dark shade, diffuse light etc. But within these perameters plants will tolerate a fair range in these intensities, except, , direct sunlight.

So, use lightmeters as a guide only.

[jerrymeola]

Jay your room is quite bright. I doubt many other members would get readings as high as yours. My house certainly would not.

Having been a photographer for 45 years I can assure you the readings are always accurate for whatever you read.

That said, you need to be taking an incident light readings for an accurate measure of the light falling on the plant. This is the little frosted globe that slides over the sensor. Reflected light readings can be misleading. Never believe your eyes. Our brains adapt to light and adjust for lower light levels.

I do all my photography outdoors under a roof right near a screen lanai. The light for 4-5 feet from the screen all looks alike but the light level can be 30-50 times stronger from 5 feet from the screen to 3 feet from the screen.

Also remember that light members are designed for photography and set to read visible light. Plants may be getting energy from other wave lengths, that we do not see or the meter does not register.

Orchids are also greatly adaptable. They often flower in less than the ideal light (although yours sounds about perfect). Many flower better in higher than normal light levels.