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Author Topic: Lights????  (Read 579 times)

Susanne42

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Lights????
« on: November 15, 2017, 01:45:16 PM »
I use CFL 6500K bulbs for the citrus room. A lot of people seem to promote those fancy and very expensive red and blue lights (Tactronic)
How important is it really for the plant to have the red and blue? Does it really matter to justify the huge price difference?
My trees are in since 10/15. Lots of growth and budding. But will this be enough for 5 to 6 month? Lights on about 12 to14 hours, temps between 15C and 24C, humidity 60% to 70% and a fan going several hours a day.
Here they are as of this morning



fyliu

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Re: Lights????
« Reply #1 on: November 15, 2017, 06:29:28 PM »
CFL is probably okay if you just want to keep things alive for the winter and don't care too much about them putting on new growth during that time.

There's another thread about grow lights that explains much better by people that know about this. I'm trying to summarize what I know.

The thing with general purpose lights is the light that comes out is over a wide spectrum, but the light that plants can absorb and use are just the red and blue. So all the other colors that get generated are wasted power.

I used to use a T5 54 watt 4ft fluorescent tube for seedlings, supposedly 5,000 lumens. It really wasn't very good for anything except seedlings. I positioned the light 2 inches above the leaves, because light energy drops off quadratically with distance. It didn't help that the light was scattered over 4 ft. Now it's a garage light and lights up the garage very well. I think the 4 tube setup would be decent for growing. That's 20,000 lumens.
https://www.hydrofarm.com/p/JSV4

There's a chart at the bottom of this page with lumen and wattage comparisons for CFL. https://www.homedepot.com/c/how_to_choose_right_compact_fluorescent_light_bulb_HT_BG_EL

Keep in mind that you have to divide the number by a lot to get to what's actually useful for plants. That's why the red/blue LEDs are worth it in the long term for power efficiency.

Susanne42

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Re: Lights????
« Reply #2 on: November 15, 2017, 07:08:01 PM »
Thank you. The thing is that the plants are actually growing really well with the cfl lambs.
But if I understand you, it cost more energy??

fyliu

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Re: Lights????
« Reply #3 on: November 16, 2017, 02:57:50 AM »
Yeah, it just costs more energy to run. Sounds like your setup is good. Indoor growth will be weaker anyway from the lack of wind stress to make it strong.

Susanne42

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Re: Lights????
« Reply #4 on: November 16, 2017, 08:30:19 AM »
even with a fan?? I never thought about this.

Daintree

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Re: Lights????
« Reply #5 on: November 18, 2017, 10:45:14 PM »
The new branches may be weaker without wind, but all my citrus are in a greenhouse with just a fan, and seem to do just fine. 
As far as light goes, I have priced it out and the grow lights and LEDS just have not come down in price enough to justify the cost, for me.
You might want to switch to fluorescent shop lights.  The fixtures and bulbs are all cheap.  I can't get T5 shop light fixtures at Home Depot yet, but as soon as they carry them, I am switching from my current T8s.  When I started my greenhouse, I could only get T12s.  The times they are a changin'.  Here is a great article from the Univ. of Alaska extension.  You may have already seen it  I have posted the link before.  I guess if anyone knows about needing supplemental light, it is Alaska.

http://www.alaskaagresources.com/wp/wp-content/uploads/vandre_fluorescent_lights_for_plant_growth_1991.pdf

Carolyn


Millet

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Re: Lights????
« Reply #6 on: November 19, 2017, 09:56:42 PM »
My greenhouse is 32-ft. W X 72-ft. L X 11-ft. H.  I have five 21" box fans running 24 seven.

nattyfroootz

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Re: Lights????
« Reply #7 on: November 20, 2017, 09:56:00 AM »
https://fluence.science/

I'm planning on investing in a couple of Fluence Rays to throw into my greenhouse for supplemental lighting. I think its around 200 or so per beam, and I only need two.  I plan on growing specialty flowers as well as subtropicals so the cost doesn't outweigh the end result that I will be getting.  Although, LED's use less energy and should provide a really nice light spectrum.   

spaugh

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Re: Lights????
« Reply #8 on: November 23, 2017, 11:37:42 PM »
They have 130 watt (300 watt HID equivelent) LED grow lamps on amazon for around 75$

The spectrum is tuned for plants and they are extrwmely efficient lumens per watt and the lumens are in the correct wavelength.  They are very reasonable for what you are getting.   HID lamps are super cheap now too since LED tech has come out.  You can get metal halide lamps really cheap.   If you get a proper grow lamp you can hang it several feet above all of your plants.

Mark in Texas

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Re: Lights????
« Reply #9 on: November 24, 2017, 09:26:47 AM »
The strengthening of trees by a gentle wind from a fan is a myth. 

PAR is what folks are after while shopping for grow lights but a MH has enough of the red spectrum and a HPS has enough of the blue spectrum to be used exclusively.  Be careful as the light industry aimed at gardeners can be quite the racket.

You're also wasting a lot of light by not having reflective panels adjacent to your trees.  Properly placed panels can increase light that the plant/tree "sees" up to 30%.

BTW, folks don't know it but the citrus growing response is photoperiod dependent.  I know a Texas citrus lover who just spent a lot of money on Cali. citrus scions, planned on keeping them in the fridge until slip stage in the spring, (no way) and I recommended a long day, short night drill, high N food, warm temps to get his trifoliata back into an active, bark slip stage.  Proof:  http://www.crec.ifas.ufl.edu/extension/trade_journals/2010/2010_Nov_supplemental_lighting.pdf
 
« Last Edit: November 24, 2017, 09:28:27 AM by Mark in Texas »

Millet

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Re: Lights????
« Reply #10 on: November 24, 2017, 11:44:38 AM »
....>The strengthening of trees by a gentle wind from a fan is a myth<....

Mark, I will have to disagree with your statement.  However, the key word of disagreement is the word "gentle", depending on what your definition of gentle is in your sentence.

Tom

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Re: Lights????
« Reply #11 on: November 24, 2017, 07:33:21 PM »
I agree with Millet. I donít know the definition of gentle winds or violent winds and everything in betweeen but I think I know some wind is necessary for strength. I have never seen a scientific explanation of no wind vs gentle wind vs more than gentle wind. It has long been thought that a gentle breeze helps strengthen very young seedlings. I have seen seedlings that jumped up too fast and they fell over or were trying to fall over. I also believe that a sometimes crying screaming baby helps develope their lungs but anything can be taken to extremes and be counterproductive ! I must add that my father loved to tell me that average didnít mean a thing to him. He said you could have one foot in a fire and one foot in a bucket of ice but average didnít mean a thing. I always laughed, every single time ! He died 12-31-87 but I still think about him a lot. Tom

MarcV

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Re: Lights????
« Reply #12 on: November 25, 2017, 07:11:59 AM »
I use Sylvania Grolux lamps as artificial lighting for my plants. They fit in an ordinary CFL armature but have a spectrum that is specifically tuned for plant growth, emitting mostly blue and red light. They appear pink to the eye when they are lit...

http://www.sylvanialighting.com.au/products/lamps/grolux-t5-t8#.Whlc2TdrxlY
...but I could be wrong...

Mark in Texas

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Re: Lights????
« Reply #13 on: November 25, 2017, 08:26:00 AM »
....>The strengthening of trees by a gentle wind from a fan is a myth<....

Mark, I will have to disagree with your statement.  However, the key word of disagreement is the word "gentle", depending on what your definition of gentle is in your sentence.

Millet, on what botanical basis, cause and effect, do you base that on?  If it's mechanical such that the wind is quite gusty then yeah, it might create fissures in the bark especially if the tree is young.  My trees in the greenhouse are quite woody and protected from wind.  No fans except for the breeze from the swamp coolers.

Millet

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Re: Lights????
« Reply #14 on: November 25, 2017, 10:15:07 PM »
Mark in Dr. Carl E. Whitcomb Ph.D, a professor at the University of Oklahoma, and owner of Root Maker Corporation, in his book "Plant Production in Containers-!!" (an excellent book) he writes...."Place your trees outside in full sun and full wind.  You want the trunks and branches to bend in he wind, as the more the tree flexes the larger in diameter they become which has been confirmed by excellent research"...... 
« Last Edit: November 26, 2017, 12:45:04 AM by Millet »

Mark in Texas

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Re: Lights????
« Reply #15 on: November 27, 2017, 09:46:44 AM »
Still would like the reason for it.  A gentle wind is not gonna do it but even still there is one spindly red oak I have in the backyard that gets its butt kicked from gusty strong winds coming off a south hill out of a valley.   It was planted the same time as the other backyard oaks.

I grow 1,000s of Christmas trees from liners, pines and cypress.  Some were staked, some not.  I only notice growth differences based on whether or not I feed them. 

Here's a study without the botanical whys.  http://ceventura.ucanr.edu/Gardening/Coastal/Landscape_578/Bending/
« Last Edit: November 27, 2017, 10:07:18 PM by Millet »

Millet

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Re: Lights????
« Reply #16 on: November 27, 2017, 10:12:02 PM »
Thanks for the link.  I would add, the quality of a tree is not how high it is, but rather the health of it trunk.   A good tree should have a trunk shaped like a good deep sea fishing rod.  Wide at the bottom tapering toward the top.

SoCal2warm

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Re: Lights????
« Reply #17 on: November 28, 2017, 01:18:58 AM »
I've found that for small enclosures, you may as well use incandescent bulbs because plants need all that heat. While incandescents are supposedly "less efficient", an incandescent is no more less efficient if you are also using an electric heating pad inside that enclosure. 100% of the energy is converted to both heat and light. Fluorescents and LEDs don't really generate enough heat to keep it warm enough in there during winter time. I'm talking about inside the house.
(For those of you who might not know, halogens are just a different form of incandescent)

The only exception might be if you have multiple shelves inside that enclosure, with multiple different lights for each shelf, and in that case something like LED grow lights may be able to keep it warm enough, especially if combined with another type of light.

I've also found, that in actual practice, the type of light source doesn't seem to make much difference. The plant mostly responds to the amount of light. But blue light, especially the light from a CFL, is more prone to cause leaf burn at higher light intensities.
Theoretically though, I think the plants respond positively if a white light source supplemented with 660nm deep red light. Generally, you'll do best to avoid lower color temperatures, but I'm not sure plants benefit any more if the color temperature is above 4000K. It's true chlorophyll absorbs blue and red light most strongly, but that also means other color wavelengths can penetrate deeper into the leaf layer for more even and fuller photosynthetic conversion. I think adding a little bit of white is more efficient than using just all red+blue.

In terms of optimal efficiency, there are two photosynthetic peaks, one at 660nm and one at 620nm, so in terms of achieving optimal efficiency, you would want to target both (maybe in a 2:1 ratio or something like that). Generation of blue light from LEDs today is very efficient, but unfortunately blue light has the most limited leaf penetration, compared to other wavelengths, so that means it's only using some of the chlorophyl (and remember plants are also more prone to leaf burn or leaf bleaching from too much blue light).

The orange-red spectral line in a common fluorescent is very close to 620nm, if you did not know, and in any case I don't think 620nm is all that imperative if you're already supplementing with 660nm.

If it were up to me, I'd be very satisfied with a 4000K or 5000K light source supplemented with 660nm deep red LEDs, maybe in about 20-30% ratio.
« Last Edit: November 28, 2017, 01:44:45 AM by SoCal2warm »

Sylvain

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Re: Lights????
« Reply #18 on: November 28, 2017, 07:50:15 AM »
> I've also found, that in actual practice, the type of light source doesn't seem to make much difference.
Reallyt?!!

> But blue light, especially the light from a CFL, is more prone to cause leaf burn at higher light intensities.
I use a 300W CFL and the plants grow until they touch the tube without any burn.

Mark in Texas

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Re: Lights????
« Reply #19 on: November 28, 2017, 08:57:59 AM »
If you need heat and a good light source it's hard to beat HID lights.  Even the ballast gives off some heat.

Ilya11

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Re: Lights????
« Reply #20 on: November 28, 2017, 09:10:14 AM »
The world according to  SoCal2warm would be deep blue, not green.  ::)
Fortunately, chlorophylls and other pigments in leaves are able do adsorb the large part of blue light between 400 and 470 nm.
Moreover, the photosynthetic action  is more efficient with this  blue  than red light of 620-680nm.
Blue light is penetrating quite efficiently into leaves and is driving most of photosynthesis there.
Tungsten incandescent lamps are emitting too strongly in  useless infrared part , bringing life burn. There are other, more efficient ways to heat the air around your plant.
Actually, the most efficient for the plants is a combination of matched blue and red LEDs.
Best regards,
                       Ilya

SoCal2warm

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Re: Lights????
« Reply #21 on: November 28, 2017, 11:21:17 AM »
Any way that uses electricity to generate heat does not have higher efficiency than an incandescent bulb. (conversion of electricity to heat in a heating element is quite efficient and they're all the same). However, a heating pad can provide more direct application of heat to the plant, so not as much heat needs to be generated. And it's also true that all the infrared from incandescent can make leaves more vulnerable to drying out, but this is only the case when the plant is a warmer temperature than the surrounding air (so not so much an issue inside a small humid enclosure).

SoCal2warm

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Re: Lights????
« Reply #22 on: November 28, 2017, 12:08:58 PM »
I saw a video comparing side by side plants growing under red + blue LEDs compared to plants growing under all white LEDs. The plants under white LED light looked noticeably better.

It's true red + blue LED is theoretically more efficient at being converted to energy by chlorophyll. But plants have several different chlorophyll pigments and if it's all red + blue light that may be overload on merely one of the pathways plants have for converting light to energy. Although I still think light penetration into the leaf is a more important issue. If almost all the light is being absorbed by the chlorophyll in the surface layer of the leaf, that's an overload, and then the light is not making it down to the deeper cell layers in the leaf. Deep red wavelengths have some penetration but shorter blue wavelengths are very strongly absorbed. Of course leaves have the greatest transparency to green light.
They did not run the experiment in that video but I'm very sure plants would grow better under white + red LED than they would under all white.

Millet

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Re: Lights????
« Reply #23 on: November 28, 2017, 12:20:29 PM »
I'm certainly not an expert when it comes to light sources.  I go along the same path as Mark in Texas and use HID light.  I don't know if it is the absolutely best, but using it on a Dekopon last winter (Sunset to 10 PM), plus heating the soil to 80-F,  I got 5 flushes of growth. Without the light & heat maybe only 1 or possibly 2 flushes would have occurred.  Plus it is little extra heat into the greenhouse.
« Last Edit: November 28, 2017, 02:55:44 PM by Millet »

Ilya11

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Re: Lights????
« Reply #24 on: November 28, 2017, 02:30:04 PM »
I saw a video comparing side by side plants growing under red + blue LEDs compared to plants growing under all white LEDs. The plants under white LED light looked noticeably better.
There is a whole science on the light use by the plants, not just this video.
It's true red + blue LED is theoretically more efficient at being converted to energy by chlorophyll. But plants have several different chlorophyll pigments and if it's all red + blue light that may be overload on merely one of the pathways plants have for converting light to energy.
Chlorophylls A and B have absorption  spectra very close to each other. You probably refer to additional pigments , mostly carotenoid that are able to absorb longer blue radiation and transfer it to chlorophylls. They  result in improved use of blue light between 400 and 500 nm. 
 Although I still think light penetration into the leaf is a more important issue. If almost all the light is being absorbed by the chlorophyll in the surface layer of the leaf, that's an overload, and then the light is not making it down to the deeper cell layers in the leaf. Deep red wavelengths have some penetration but shorter blue wavelengths are very strongly absorbed. Of course leaves have the greatest transparency to green light.
In action spectrum measurements the difference in light penetration is already taken into consideration.  Leaves are transparent to green light because they do not contain  pigments adsorbing green light, so the green light has almost no effect. Modern white LEDs have three chromophores emitting blue light of 400-500 nm, green light of 500-570nm and red of  more than 649 nm. The green portion is almost lost, decreasing the overall efficiency by 30%
They did not run the experiment in that video but I'm very sure plants would grow better under white + red LED than they would under all white.
Best regards,
                       Ilya

 

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