Footcandles for shade house?

[Paul Mc]

So, as some of you know, I'm having a shade house for my chids being built. At 6pm, I measured about 6000 footcandles!!!!!! Oh my! My first thought was that's way too much, even for Vandas!

But then I went and measured where I kept my dendrobiums and oncidiums last year and it was exactly the same! They were fine last year except when temps went into the 100 f range for about a week.

So, I'm now wondering how important this footcandles measurement really is. Of course, I know that Vandas need higher light, dendrobiums and oncidiums usually medium, with phals at a lower end of the spectrum. But what is the max I should aim for?

I'm hoping to keep my phals on the bottom in a sheltered position from the rain, and all higher light plants on the top shelf or on the south side of the structure where more sun will come in.

Any thoughts on this footcandles/actual shade needed thing? We are scheduled to start construction in about a week once I figure out a few more details, with your assistance.

[WhiteRabbit]

[RJSquirrel]

Intermediate/Warm growing mostly seems like so 1800 to 4000 Fc's should be adequate. Ive read and learned in some odd fashion that orchids do much better below the 4000 Fc mark. BUT keep in mind that 6000 Fc isnt a constant and for most part of the day you arent going to have equatorial sun spots burnin thru your roof. 10000 fc is like full killer sun.

So 60% shade cloth should give you the 4000fc you want..you can put more shade cloth over areas or as you said hide stuff under other plants and tables. It works for me ..

I guessed Im pushing 2500 fc but in retrospect with 50% shade cloth more in the 4000 fc range myself. Its not the light you really fight its the heat being generated internally by the plants collecting the light. You have to keep the temps down when you use more light and have to have constant motion of the air. If you cant keep your space cool enough for 4000 Fc you might have to drop the lighting down some...Made sense to me anyway

[Paul Mc]

Thank you WhiteRabbit for the bump! And RJ, thank you for your thoughts. Makes perfect sense. Now to find an outdoor grade oscillating fan, lol...

I plan on measuring every hour today to see just how much light we get. We had a huge pin oak that will shelter the plants during the hottest part of the day, and the plants will have a wood fence blocking the evening sun. I was still shocked though that it was that bright and that my orchids seemed fair well in similar light all last year. At least, they did good until we hit a week or so of over 100f temps! That kinda got them.

[Paul Mc]

As a point of reference, here's the area.


And an aerial view, the spot is on the right, just about even with the end of the patio, at the edge of the stepping stone path.