Question re: LEDs - Orchid Board

butterfly_muse · #1 05-10-2013, 10:01 AM

Good morning, everyone!

I was reading through the thread and I came across Ray's LED lights that he is selling, and I wanted to know if they are too bright for Phals? I asked in the thread, but I don't think anyone saw, lol.

I will be moving at the end of the month and our apartment will now only have shaded NW facing windows, so I know I will need to supplement for all of my plants. I've got a begonia that takes full-partial sun, as well as two African violets, an ivy (one of those standard long growing things you see at offices) and 7 phals. Would those LEDs be too bright? If I hung them a little higher so as to allow the begonia and African Violets to shade the phals, would that work or would I have to have them near the leaves? How many would I need? From what I can tell they're quite strong, so I thought maybe only one, 2 at most since I have a small setup. My plants are grown on a baker's rack.

Any help you could give would be really great! Thanks!

Ray · #2 05-10-2013, 10:11 AM

No light is "too bright" for any plant. It's all a matter of initial intensity and distance.

Light intensity decreases by the by the inverse square of the distance from the light source. If you have a high-light plant growing comfortably a foot from the light, then at two feet from the light, the intensity will be 1/4 as strong, so fine for lower-light plants.

I have paphs, phlas and AVs growing and blooming under one of my 17W lamps at a distance of 15" from the lamp to the foliage. At that height, it covers an area about 30" square.

If I wanted to grow higher light plants under it, I'd decrease the distance.

butterfly_muse · #3 05-10-2013, 10:23 AM

Quote:

Originally Posted by Ray

No light is "too bright" for any plant. It's all a matter of initial intensity and distance.

Light intensity decreases by the by the inverse square of the distance from the light source. If you have a high-light plant growing comfortably a foot from the light, then at two feet from the light, the intensity will be 1/4 as strong, so fine for lower-light plants.

I have paphs, phlas and AVs growing and blooming under one of my 17W lamps at a distance of 15" from the lamp to the foliage. At that height, it covers an area about 30" square.

If I wanted to grow higher light plants under it, I'd decrease the distance.

Alright, great, thanks!

I'm glad they're working out, florescent light bothers my eyes so I'm really happy there is a sufficient alternative. Thank you!

Discus · #4 05-10-2013, 10:38 AM

If you want to be able to adjust the distance between your plants and your lights, you have two options - move the plants or move the lights!

It's quite useful to be able to know when a plant is "happy" with a given light intensity (e.g. what the right leaf colour is), but that usually takes a while to manifest (weeks or even months sometimes).

You can of course use one of several methods to find out how much light there is (light meters, camera exposure times, the "shadow test", cellphone apps etc), but be aware that with some light sources (that are not sunlight) many measurements won't be able to accurately assess the equivalent "foot candles" worth of "natural" (sun) light, depending on the "algorithm" and the sensor involved in doing the reading.
LEDs are inherently not full spectrum lights, so they're probably a bit more "intense" per watt than a full range bulb (as less of the light is "wasted" in frequencies that are less useful to the plants, and LEDs are also very efficient at turning current into light). Of course, most lights try to come close to the colour rendering of sunlight (otherwise things can look decidedly Odd), but pure "grow" ones may not do so, as some people are more concerned with efficiency than aesthetics!

Re: fluorescent bothering your eyes, it may be particular bulbs (colour type like e.g. "warm white") or types of bulbs (T5 vs T8 etc.) that bother your eyes; I find most office lights quite unpleasant, but the T5 ones I have on fishtanks and above some plants are less objectionable, particularly when they have good electronic ballasts.

butterfly_muse · #5 05-10-2013, 10:41 AM

Does the light spectrum covered by the LEDs cover what is needed by plants to grow, or would I have to get a different kind of light to supplement those wavelengths? (Sorry, I know nothing about growing under lights, we have a South window right now so I never had to worry about it before, lol).

I do want my plants to grow and prosper, but I also have a couple mystery plants that I am dying to see spike at some point so I can find out what color they are, lol! I know at least with Phals that leaf color will vary with light intensity, and given the growth I've seen recently on my other plants, I know that they are currently getting enough. I would hope that they would respond similarly under artificial light and I'd be able to adjust accordingly. =\

Discus · #6 05-10-2013, 11:05 AM

Most orchids want to be a sort of nice grassy green; IME phals seem to like having a slightly darker green.

wrt the growing light spectrum, you can pretty much bet Ray's lights are good enough to supply everything the plant needs to grow and flower. What the CRI is like, I have no idea, having not seen these units.

But in any case CRI != growth, it equals "makes things look (to human eyes) like they're under sunlight" - but plant photosynthetic pigments don't use all those frequencies of light.

---------- Post added at 03:58 PM ---------- Previous post was at 03:54 PM ----------

Have a look at this graph, comparing what light is "natural" (the black line) vs. what plants use:

---------- Post added at 04:01 PM ---------- Previous post was at 03:58 PM ----------

If you're not too familiar with plant photosynthetic pigments, Chlorophyll A & B are what all plants pretty much have, the others are so-called "accessory" photosynthetic pigments which increase a particular plant's ability to use other light energy (you can think of them a bit like antennae that let you pick up a new TV channel, only instead of different movies, you're picking up more light energy). I can't recall off the top of my head what accessory pigments orchids have.

---------- Post added at 04:05 PM ---------- Previous post was at 04:01 PM ----------

You might find this article useful: Orchid Karma – Light and of course the various articles Ray himself has published on First Rays' Free Info under "growing conditions".

butterfly_muse · #7 05-10-2013, 11:10 AM

Awesome, thank you!

Discus · #8 05-10-2013, 11:14 AM

Also, if you have a look on Ray's sale page for these lights, they have a spectrum chart

I'd love to know if the lack of blue vs. absorption spectrum (probably UV actually) makes a significant difference, particularly for more shade-adapted plants.

butterfly_muse · #9 05-10-2013, 11:15 AM

My fiance was actually just looking at that. He's an engineer so when he's faced with a problem like this one, he goes crazy with "How do I fix this problem?" Lol

Discus · #10 05-10-2013, 11:18 AM

Oh, and if you were wondering why plants look green, compare the absorption spectrum to the available light - there's a big gap in the green, so they're ending up not absorbing this colour, and as that's what ends up being reflected back into your eyes, they end up that colour - green!

---------- Post added at 04:18 PM ---------- Previous post was at 04:17 PM ----------

re fiancée, LOL.
For total adjustments of overall levels, it's usually easier to move lights than plants, but individual plants can be "moved" by doing things like putting them on top of shelves/upside down pots, which gives you flexibility when you grow different things. Phals and paphs go at the bottom