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All About Light - Information all here

Ok so I was kind of confused on which lights to get for my plants. I was confused about the difference between lumens, wattage, color temperature, and how it all played to my plants. This thread is to provide good information for all pepper growers to inform them of the right type of light to use on their plants. I did the research just for you so take the time to read this up to increase your plants health and look.

Understanding Light and Wavelength

Ok first of all lets define what light actually is. Sun light is a combination of many different wavelength lights transmitted from the sun. This combination of light is called a spectrum. A spectrum defines all aspects of the characteristic of a given light source. The most logical thing to point out is that sun light is the best quality light you can give for your plants. If you are able to put your plants outside then do it! Otherwise if your like me you need to use a light inside to grow your plants.

I bet when you decided to grow your plants inside you prolly went out a bought a light bulb and plugged it into your desk lamp and turned it on. However this isn't the same as regular sunlight. Anyway your at the store and see all these different lights and are confused what to buy. There are daylight, cool daylight, warm daylight, and weird temperatures such as 2700 K, 5000 K, or 6400 K and you have no idea what to buy!

The thing is there isn't a one light bulb fits all solution and I will explain why that is the case. Sunlight is what is called a continuous light source. That means that all the wavelengths from 400-700 nm are all present in an equal fashion in regular sunlight. Most people on the forum may say that CFL is the best bulb to buy. However the CFL is not a continuous light. The CFL bulb works by combining 3-4 types of phosphorous gas inside the bulb and sending an electric signal through that gas, which caused the gas to ionize and produce light. The 3-4 types of gases all give of a dominant wavelength. Therefore on a spectrum you will see lines of strong light while some light wavelengths are very dim or non-existent.

Lets look at the spectrum for sunlight using a basic diffraction grating spectrometer. These pictures are taken from here

sun_spectrum1.jpg


As you can see the color continuous flows from one color to another. This is what we call a continuous light source.

Lets look at a fluorescent tube bulb spectrum

fluorescent_spectrum.jpg


As you can see the color is continuous but some color's show up brighter than other colors. These are the dominant wavelengths.

Lets look at a CFL, compact fluorescent bulb.

cfl_spectrum.jpg


As you can see alot of the color's are absent in this type of bulb. This bulb only showcases the dominant wavelengths while the intermittent wavelemgths are either too dim to see fully or absent.

But What Does This Have to Do With My Light Bulbs?

Understanding light spectrum is so fundamental in understanding on what light bulb to get because most bulb company's fabricate an equivalent color temperature that describes the mean temperature of the light given off. This does not mean that only that specific wavelength is given off but a normalized average. Wavelength can be expressed as a temperature in Kelvin by using Wein's Displacement Law which is the basic starting argument for arguing light is a wave (quantum mechanics).

Basically we want to find a bulb that is similar to sun light and too that we need to compare the spectrums of the bulb with sunlight to find a match. This bulb then should be sufficient to feeding your plants.
 
Types of Bulbs

Information take from here

Sunlight Spectrum:

outdoor_daylight.jpg


Incandescent Spectrum:

incandescent.jpg


"Daylight" Spectrum Halo-Phosphorus CFL

daylight.jpg


"Cool Daylight" Spectrum Halo-Phosphorus CFL

cool_white.jpg


"Warm Daylight" Spectrum Halo-Phosphorus CFL

warm_white.jpg


Now comparing these three things we can see that the "daylight" is the best fit to the sunlight spectrum because it has more blue/green light in it. Blue light is necessary for plants to go fat and short while red light is necessary for plants to grow thin and tall. Both types of light are necessary and there is no one bulb fits all solution.

Now lets look at some comparing bulb spectrums. These bulb's can be identified at your local store by looking at the manufacturer model number on the back of the box.

Bulb Model: SPX50 Tri-Phosphorus CFL
SPX50.jpg

Bulb Model: SPX41 Tri-Phosphorus CFL
SPX41.jpg

Bulb Model: SPX35 Tri-Phosphorus CFL
SPX35.jpg

Bulb Model: SPX30 Tri-Phosphorus CFL
SPX30.jpg

Bulb Model: SPX27 Tri-Phosphorus CFL
SPX27.jpg
 
Bulb Model: SP65 Tri-Phosphorus CFL
SP65.jpg

Bulb Model: SP41 Tri-Phosphorus CFL
SP41.jpg

Bulb Model: SP35 Tri-Phosphorus CFL
SP35.jpg

Bulb Model: SP30 Tri-Phosphorus CFL
SP30.jpg


From these bulbs we can see that in order to get good blue and red light we will need an SP65 or an SPX50 type CFL in order to get the right spectrum. Also the "daylight" specified bulb seems to be closer to the sunlight spectrum that "cool daylight".

I will argue a point of adding a incandescent bulb with a "daylight" bulb would be the most beneficial in aiding plant growth and development.

*More to come in following posts :D*
 
That's way to scientific for me. I use 2 tube 4' T8 shop lights from Lowes with 6500k bulbs and have had great results. They're are a whole lot of fancy options out there that do well but cost. I'm on my first year starting seeds and have had great luck with a lot of good advice from folks here. Hope my luck continues. If you're just starting out growing basic is good.
 
That's way to scientific for me. I use 2 tube 4' T8 shop lights from Lowes with 6500k bulbs and have had great results. They're are a whole lot of fancy options out there that do well but cost. I'm on my first year starting seeds and have had great luck with a lot of good advice from folks here. Hope my luck continues. If you're just starting out growing basic is good.

good results are not the best results :)
 
so how about metal halide? they also got a wide spectrum.
SpectralDistribCrt.jpg


Metal halide lights are used for the first (or vegetative) phase of growth as they have a bluish light.

Blue spectrum light may trigger a greater vegetative response in plants.

High pressure sodium lights are used for the second (or reproductive) phase of growth as they have a reddish light.

Red spectrum light may trigger a greater flowering response in plants. If high pressure sodium lights are used for the vegetative phase, plants grow slightly more quickly, but will have longer internodes, and may be longer overall.

and then we have LED full spectrum grow lights which supply the blue and red part of the spectrum.
 
What colors should I use for my grow light? – Believe it or not most people when building a light think that they need either a green or white light. This is well for the most part wrong as green light is not easily absorbed by plants as they reflect most of the light because of their green chlorophyll, and the white light does not contain enough amounts of correct colors on the color spectrum to grow plants effectively. So which colors should I use? In short you would be best going with blue and red. There is a lot of talk going on about whether or not other parts of the color spectrum should be added but, there are a lot of successful lights that only use blue and red , the reason that this is true is because this is where most of the uptake for photosynthesis happens in plants. Most of the peaks on graphs show uptake being in the blue and red areas.
Chlorofilab-300x125.png
 
It depends on what you are trying to achieve. I also use 6500K T8 tubes, but they are just to start seedlings. Once weather permits they get pure sunlight. Producing fruit under lights is a whole different thing. I guess I haven't heard of many people using incandescent bulbs for growing. They work good for heating up a germination box though.
 
I have some problem with the "Sunlight is X, so you need X to grow good plants" argument, since it doesn't take into consideration what the actual plant requires and that can differ depending on the stage of growth, as well as the plant type.

That said, a mix of multiple light-types seems to be the best bet to feed both Chlorofil A & B.
 
I guess I don't believe it. I have spent many hours reading about lighting and the focus is always on blue or red.
very true. :) thats what i was getting to :)

I have some problem with the "Sunlight is X, so you need X to grow good plants" argument, since it doesn't take into consideration what the actual plant requires and that can differ depending on the stage of growth, as well as the plant type.

That said, a mix of multiple light-types seems to be the best bet to feed both Chlorofil A & B.
yeah there are led lights with mix of red and blue spectrum for growing :)
 
yeah there are led lights with mix of red and blue spectrum for growing :)

Even then, I'd mix types - LEDs from company A may well have different output from those of company B.

Coming from a photography background, you can see the difference (both actual output power and frequency) in light types, brands, models and even manufacturing runs, and unless you are paying big dollars (or testing the lights yourself), the stated output is rarely close to the actual output.

Mixing lights will often give you a greater range than you would think.
 
Even then, I'd mix types - LEDs from company A may well have different output from those of company B.

Coming from a photography background, you can see the difference (both actual output power and frequency) in light types, brands, models and even manufacturing runs, and unless you are paying big dollars (or testing the lights yourself), the stated output is rarely close to the actual output.

Mixing lights will often give you a greater range than you would think.
well what i was trying to tell is that those lamps are made specially for growing so the color temps and spectrum are controlled. if it does vary also, is should be in the tolerance range where it is still useful for the plant :)
led's are monochromatic light source so they are manufacture to produce specific light range.
for example see lamps below

51wN7bZ9tWL.jpg

240W Lighthouse Hydro BlackStar Grow Light 6 Band 3W Chips Flowering 240 Watts

514FU4lDjBL.jpg

180W Lighthouse Hydro BlackStar Grow Light Tri Band 2W Chips Flowering 180 Watts
 
I'm using a 430W 2300K 56,000 (have to double check those stats) Lumen HPS for some of my plants, and 6500k 48" T8's for others, the Ground Cherry seedlings are growing much quicker under the warmer, redder HPS. I've also noticed a huge jump in growth in the majority of plants I placed under the HPS, Probably due to the warmer temp.
 
"Daylight" Spectrum Halo-Phosphorus CFL with incandescent should give you all parts of the spectrum that sunlight produces and more!

I have some problem with the "Sunlight is X, so you need X to grow good plants" argument, since it doesn't take into consideration what the actual plant requires and that can differ depending on the stage of growth, as well as the plant type.

That said, a mix of multiple light-types seems to be the best bet to feed both Chlorofil A & B.

Plants evolved using the sun so why shouldn't they grow best in what they spent billions of years in, with natural selection processes eliminating weaker strains?

Almost all CFL lights do not contain the full red spectrum. What is most important is the high purple/blue and high orange/red light. Look at the spectrum graph and compare what your light provides.
 
Plants evolved using the sun so why shouldn't they grow best in what they spent billions of years in, with natural selection processes eliminating weaker strains?

Because it is a very generalised statement, and we can't drag a star inside our grow-rooms.

All plants are different, have different needs when it comes to light, earth, water etc. Each plant will grow best when given the light, earth and water requirements that match its particular needs. With chillies, some love heaps of direct sunlight, the more the better, and some like some shade. If you are trying to duplicate that plants needs, shouldn't you be using a light that matches, rather than trying to match direct sunlight?

People are getting very technical when it comes to lights for their plants, deciding that model A is better than model B, because it has more of the 400nm. But they don't know why they think they need that. They use information based on the study of plants. Not a specific plant, but just plants in general. Which is where the problem starts to grow.

Until someone comes up with the light-needs of the Capsicum family, then there is no real way to buy lighting that will match its actual needs. Add that to only going off manufacturers stated specs (which, as I said, won't be accurate unless you are buying expensive gear) and it is all starting to be a bit of a crap-shoot.

I'm not having a go at anyone, just suggesting that you need all of the information before you can accurately state that the type X light is best for the particular variety of plant you are growing.

Buy whatever lights you think will work, and if they improve your plants, great - coz that's the aim. :)
 
wow.. all these posts about lights can get very complicated right from the very first page.
Makes me appreciate the sun even more.
I think i'll go for LED (mixing red and blue), but high power LEDs are still very pricey, and i don't think low quality LED will do.
But for the time being, i'll try to have more sunlight (the best light there is) for my plants whenever possible.
 
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