Do orchids need UV light?

[susiep]

I am building a new shade house for my 'chids. They have been grown outside under screen. Or in the shade of palm trees. I had to add a plastic sheet (3mil) over the top of the old shade house because the plants were getting too much water leading to fungal rot.

My question is: Will my plants miss the UV light they are getting now if I add a solid plastic top to the new shade house which blocks almost 100% of UV rays?

I was looking at this product at Home Depot.
http://www.palramamericas.com/docs/u...v_04-15-08.pdf

[Ray]

No.

[susiep]

Ok, thanks.

[Rivka]

i know this is a very old thread, but i have often asked myself the same question, in my case because i am fond of the frosted window cling films for privacy and to soften the quality of light.

Ray can you elaborate on why this is fine for orchids? would love to understand it a bit more, i figured it cant be to great for them, but that was not really based on any facts.

[DavidCampen]

In my solarium all of the light goes through either triple wall polycarbonate or double pane windows both of which have been treated to absorb UV (and the polycarbonate absorbs UV even without a surface treatment). I see no evidence that the plants miss the UV. Lots of greenhouses now are made with multiwall polycarbonate that absorbs the UV.

[spetrizio]

UV is definitely not needed for plants, but infrared could be important for flowering.
I do not know for polycarbonate, but many window films block almost 100% of infrared.

[Magnus A]

IR light is just heating the orhid as UV light has the energy to damage biological tissue.

There are protection mechanisms for UV light in plants and I believe that some species can react possitive or negatively on what these mechanism do.
I have heard that some rupicolous laelias can flower better if exposed to unfiltered sun light compared to strong artificial light and it should be the UV triggered protection mechanisms that is behind the better flowering, though there are no research done on this to my knowledge.

The metabolism in plants exposed to UV light is changed and maybe this can have an effect.

[Rivka]

There are very few, very costly window films that block IR light totally or even a lot. That is a real specialty.
Correct me if I'm wrong but I had looked into that big time when looking to reduce heat build up in a airstream trailer.

Heck there are a things that block all visible light but NOT IR! They make headlight and spotlight covers for night military operations like that. IR is very penetrating.

This whole topics is really interesting, I would love to learn more about orchids and their interactions or needs in different parts of the light spectrum. Anyone got good reading for me?

[spetrizio]

regarding IR:
"Plants require mostly blue and red light for photosynthesis, but for flowering, infrared light is also needed. ... Foliage plants grow well under cool-white fluorescent lights, while blooming plants require extra infrared light. This can be supplied by incandescent lights or special horticultural fluorescent lights." (Texas A&M University System)

link:
Light, Temperature and Humidity

[Magnus A]

Originally Posted by spetrizio

regarding IR:
"Plants require mostly blue and red light for photosynthesis, but for flowering, infrared light is also needed. ... Foliage plants grow well under cool-white fluorescent lights, while blooming plants require extra infrared light. This can be supplied by incandescent lights or special horticultural fluorescent lights." (Texas A&M University System)

link:
Light, Temperature and Humidity

To be a pain, a webpage is not a good reference... I have tried to find anything in the scientific peer reviewed journals and there are VERY little on orchids. There is though material that show very different behavior dependent of what kind of species investigated. If I remembered correctly there are examples on flowering plants that do flower less good when exposed to a large portion of IR light.