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Do plants grow as well under artificial light? - no value added article
- Thread starter Cerberus
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AlabamaJack
eXtreme
I think that is stating the obvious to most of us growers on this forum...that's why we use a combination of blue and red spectrum lighting in our inside grows...
AlabamaJack
eXtreme
no problem C....been there done that... 
Hey AJ how does the blue and red lights help the plants? I dont know this because Im a first time grower
I've done a lot of growing indoors and outdoors. I even ran one of three aeroponic commercial greenhouses in North America for about 7 years (if you'd like a pic just ask - basil was my staple crop). Here's my experience.
While one can go all-out indoors, using 80-100 watts/Sq Ft, CO2 supplementation (1200+ ppm), hyper-aerated solutions, <5 micron nozzles, and so on, it is VERY, VERY hard to beat mother nature in terms of light. Even with the 100% consistency of an indoor operation, there is something about the balance of outdoors- the combination of rain, varying wind, extreme sunlight, etc., that plants respond to that can give results unmatched by the most advanced indoor setup.
That being said, there are a lot of factors outside that one avoids inside, but much like life, everything is a compromise. The hottest and best tasting peppers I've ever grown were outside. The best cilantro I've ever tasted I grew outdoors. Ditto for most other crops. Granted I was growing in a soil-less medium, much like what is used on green roofs (which is a great starter mix for outdoor growing if amended/modified properly).
As for the red/blue question, much like modern crystalline solar panels, for whatever reason the plants use certain spectra of light more efficiently than others - blue and red tend to be the most efficient response wavelengths. This is why some folks are using LED arrays to grow plants (LED's produce VERY narrow bands of light, ex: 635 nanometers = green). There is still a lot of research to be done in this field IMHO.
One nice advantage of the sun is the wide array of ultraviolet spectra available to the plant. I've found that a lot of odoriferous plants (basil, cilantro, oregano, etc.) produce more volatile constituents (terpines, etc.) and certain oils in a linear response to UV wavelengths. I did a controlled study of this in my greenhouse where ~1,000 sq ft of floor area was covered by a type of plastic that eliminated over 90% of UV. I had some control plants and UV-hindered plants sent to Penn State Ag for testing, and sure enough, many constituents were 10-50X more present in the basil grown that did not have the UV sprectra removed.
If you're growing indoors, you're probably best off with fluorescents (make sure the bulb is rated somewhere around 3000K) or a small halide or HPS. For peppers, more light is better. Don't be talked unnecessarily into HPS (though HPS's put out a little more light per watt but they produce little to no UV, unlike a halide) because "the red spectrum helps flowering". That theory comes from pot growers, whose plants' flowering differ a bit from peppers as far their biological flowering mechanism is concerned. Folks say that red light helps promote auxin production, which leads to bigger flowers, etc., etc. While this is a small piece of the puzzle, don't get too hung up on specifics. Peppers grow all over he world in different conditions. As long as you fulfill: Enough light, enough nutrition (per Le Chatelier's law of minimums), enough aeration for the roots (important for peppers), proper temperature, proper humidity range & the right amount of water you should be successful.
A good rule of thumb for indoors is to use 50+ Watts of lighting per square foot of area (MH, HPS or Fluorescent). Go with that and you should be alright.
Good luck!!
While one can go all-out indoors, using 80-100 watts/Sq Ft, CO2 supplementation (1200+ ppm), hyper-aerated solutions, <5 micron nozzles, and so on, it is VERY, VERY hard to beat mother nature in terms of light. Even with the 100% consistency of an indoor operation, there is something about the balance of outdoors- the combination of rain, varying wind, extreme sunlight, etc., that plants respond to that can give results unmatched by the most advanced indoor setup.
That being said, there are a lot of factors outside that one avoids inside, but much like life, everything is a compromise. The hottest and best tasting peppers I've ever grown were outside. The best cilantro I've ever tasted I grew outdoors. Ditto for most other crops. Granted I was growing in a soil-less medium, much like what is used on green roofs (which is a great starter mix for outdoor growing if amended/modified properly).
As for the red/blue question, much like modern crystalline solar panels, for whatever reason the plants use certain spectra of light more efficiently than others - blue and red tend to be the most efficient response wavelengths. This is why some folks are using LED arrays to grow plants (LED's produce VERY narrow bands of light, ex: 635 nanometers = green). There is still a lot of research to be done in this field IMHO.
One nice advantage of the sun is the wide array of ultraviolet spectra available to the plant. I've found that a lot of odoriferous plants (basil, cilantro, oregano, etc.) produce more volatile constituents (terpines, etc.) and certain oils in a linear response to UV wavelengths. I did a controlled study of this in my greenhouse where ~1,000 sq ft of floor area was covered by a type of plastic that eliminated over 90% of UV. I had some control plants and UV-hindered plants sent to Penn State Ag for testing, and sure enough, many constituents were 10-50X more present in the basil grown that did not have the UV sprectra removed.
If you're growing indoors, you're probably best off with fluorescents (make sure the bulb is rated somewhere around 3000K) or a small halide or HPS. For peppers, more light is better. Don't be talked unnecessarily into HPS (though HPS's put out a little more light per watt but they produce little to no UV, unlike a halide) because "the red spectrum helps flowering". That theory comes from pot growers, whose plants' flowering differ a bit from peppers as far their biological flowering mechanism is concerned. Folks say that red light helps promote auxin production, which leads to bigger flowers, etc., etc. While this is a small piece of the puzzle, don't get too hung up on specifics. Peppers grow all over he world in different conditions. As long as you fulfill: Enough light, enough nutrition (per Le Chatelier's law of minimums), enough aeration for the roots (important for peppers), proper temperature, proper humidity range & the right amount of water you should be successful.
A good rule of thumb for indoors is to use 50+ Watts of lighting per square foot of area (MH, HPS or Fluorescent). Go with that and you should be alright.
Good luck!!
AlabamaJack
eXtreme
I think everyone knows that growing in the sun is better than growing under artificial light...at least on this forum...
but there are times, like freezing december-february that you can not grow outside (and most of us do not have commercial greenhouses) and long season peppers require early indoor starts to be successful...plus the fact growing cutback plants is a good practice to get into providing massively productive 2[sup]nd[/sup] and 3[sup]rd[/sup] year plants..
I use lumens/ft[sup]2[/sup], rather than watts/ft[sup]2[/sup] because different kinds of lighting (fluoro, CFL, HPS, MH, LED, etc.) emit different amounts of lumens/watt. A good rule of thumb for peppers is that 3,000 lumens/ft[sup]2[/sup] light will provide enough light to grow a pepper plant to maturity. And I achieve 3K lumens/ft[sup]2[/sup] using CFLs at 47.5 watts/ft[sup]2[/sup].
The more efficient the bulb, the more lumens/watt it produces.
as far as your comments on HPS go, they are more efficient than other types of lighting with maybe the exception of LEDs...
but there are times, like freezing december-february that you can not grow outside (and most of us do not have commercial greenhouses) and long season peppers require early indoor starts to be successful...plus the fact growing cutback plants is a good practice to get into providing massively productive 2[sup]nd[/sup] and 3[sup]rd[/sup] year plants..
I use lumens/ft[sup]2[/sup], rather than watts/ft[sup]2[/sup] because different kinds of lighting (fluoro, CFL, HPS, MH, LED, etc.) emit different amounts of lumens/watt. A good rule of thumb for peppers is that 3,000 lumens/ft[sup]2[/sup] light will provide enough light to grow a pepper plant to maturity. And I achieve 3K lumens/ft[sup]2[/sup] using CFLs at 47.5 watts/ft[sup]2[/sup].
The more efficient the bulb, the more lumens/watt it produces.
as far as your comments on HPS go, they are more efficient than other types of lighting with maybe the exception of LEDs...
Here's that picture of my old aeroponic greenhouse I was talking about. I'm at the back end of the first structure. Total floor space amongst all three was ~19,000 SF. An old-school computer (it was a 486 PC) running Linux was fed environmental information through the joystick port (all in ohms - temperature, sunlight intensity, humidity, etc.) and the printer port was used to control a bank of 32 relays, all running 24 VAC that in turn controlled real world events (exhaust fans, evap cooling, tube fogging).
Inside those vertical tubes was........... nothing. Just air, with a <5 micron misting nozzle operating at 150-225 psi. Depending on the conditions, it could fire for 5 seconds once every few hours during cooler nights, or for 120 seconds every 5 minutes during sunny, 90-degree plus weather. A lot of air was available to the roots and growth rates were astounding. Plants on the left are 2 days from transplant in 3/4" oasis wedges, plants on the right are 9 days from transplant. In August, I could go from tiny seedling to 1/4=lb of leaf super-bushy basil plants in 19-20 days.
Sorry for not putting my face in the picture. I'm *done* with "face mining" software such as is prevalent on Facebook where emerging facial recognition programs are taking hold. Sophie the Mastiff's head is much more fun to look at anyhow....
Inside those vertical tubes was........... nothing. Just air, with a <5 micron misting nozzle operating at 150-225 psi. Depending on the conditions, it could fire for 5 seconds once every few hours during cooler nights, or for 120 seconds every 5 minutes during sunny, 90-degree plus weather. A lot of air was available to the roots and growth rates were astounding. Plants on the left are 2 days from transplant in 3/4" oasis wedges, plants on the right are 9 days from transplant. In August, I could go from tiny seedling to 1/4=lb of leaf super-bushy basil plants in 19-20 days.
Sorry for not putting my face in the picture. I'm *done* with "face mining" software such as is prevalent on Facebook where emerging facial recognition programs are taking hold. Sophie the Mastiff's head is much more fun to look at anyhow....