How many watts per square foot?

[Hemposapien]

I am just wanting to know ideally how many watts per square foot is needed to fully flower 4 plants?

My current set up is TS1000 by Mars Hydro but I just upgraded to a TSW 2000 by Mars Hydro. The TS 1000 is 150 W and the TSW 2000 is 300 W. My tent is 2.7*2.7*6ft HS80 Secret Jardin grow tent.

 

[automan2]

I'm running a ts1000 + 2 cobs in a 2x3x5...280w in 6 sq ft...getting the lights close enough during bloom seems to be key.

 

[Hemposapien]

I'm running a ts1000 + 2 cobs in a 2x3x5...280w in 6 sq ft...getting the lights close enough during bloom seems to be key.

Cool, I think the TSW 2000 will do the trick then.

 

[Olderfart]

I found that more than ~300 watts in my 9 sq. ft. was probably too much, so I think that you have lots. Go easy at first, and back off at first sign of taco.

Good luck with the grow.

 

[Death The Cultivator]

At minimum, 20 watts of full spectrum and 50 watts at the max. I would use the ts2000. That light puts you at 45watts

 

[Sqwirlman]

I am pretty green still when it comes to growing but my first grow wasn’t bad. I vegged and flowered at 25 watts per sqft. I had good results. Since then I have added some auto cobs and I am just over 50 watts per sqft and holy cow the girls are on fire. I have a 4x4 tent. The flowers are rock hard and not fluffy like my first grow. Some of it is due to changing from fox farms to mega crop but getting to that 50 watts per sqft for flowering is key. Bellow is the link to my current grow. It has a couple pictures from my first grow. I started out with just my California light works solar extreme 500 which pulls 400 watts at the wall. I now have 8 3500 k auto cobs also.

https://www.autoflower.org/threads/second-autoflower-grow-mega-crop.73651/

 

[Son of Hobbes]

Forget watts, look at PAR/PPFD.

PAR (Photosynthetic Active Radiation) is light that falls between 400nm (heavy in the blues) and 700nm (heavy in the reds) spectral region (better known as spectrum.) PAR light defines the type of light needed to support photosynthesis.

There are two important qualities to look at in PAR light for growing, one is the amount (what we would consider intensity) and the other is spectral light quality (which is referring to the spectrum the light is producing, often noted with spectrum graphs that you may have seen while looking at grow lights.)

PAR is quantified by Photosynthetic Photon Flux Density (PPFD,) measured in micro-mols per second (μmol/s), indicating how many photons in this spectral range fall on the plant each second.

If you’ve ever looked up grow lights of any kind, nearly all of them have some sort of information on the PAR/PPFD, usually PPFD is a coverage chart that shows the PPFD rating at certain heights and spreads of the light over a certain area of coverage.

Depending on the type of lighting and how it’s mounted, PPFD can be fairly homogenous (spreading the light out equally, giving near equal coverage in the recommended space for the size of the light,) but many lights tend to focus a high amount over the center of the light (where it beams down from the source,) then the numbers drastically lower as the light spreads out inefficiently (which is why it’s important to understand the numbers for coverage as well, especially if a vendor is claiming high PPFD numbers (which may be accurate, but you need to understand the spread correctly.)

Generally the higher the PPFD number the more intense the light is. If the light intensity is too high (by delivering too many photons whether per second or over the spread of the day) the chlorophyll pigment in the leaves gets damaged by photo oxidation (light bleaching.) This is why seedlings and young plants don’t typically need as strong/intense of lights (you don’t feed an infant a t-bone steak, right?) but instead gradually increasing the power/intensity through the life cycle of the plant. Dimmers are becoming popular on many grow lights exactly for this reason (or controlled via box/board.) There are grow lights and add-on electronics that are able to literally simulate and artificial sunrise and sunset with dimmers. Many LED grow lights use lenses, reflectors, optical diffusers, etc, to help control the spread and the beam of the light. HID lighting uses reflectors (winged, parabola, vented hoods,) to help control the spread of light.

You can find varying charts on PPFD recommendations for stages of growth, here are two examples (and you can see how close in range they are for the most part:

200-400 PPFD: Great for seedlings, clones, and mother plants.
400-600 PPFD: Great for early to late stage vegging cycles.
600-900 PPFD: Great for beginning to end of flowering cycle.

The bottom chart came from Fluence (a very well known provider of lights: )

I'd recommend looking at numbers like these, not wall watts (which do factor in part of the equation, but the efficiency of the light and technology used does too.)

 

[Sqwirlman]

A

Forget watts, look at PAR/PPFD.

PAR (Photosynthetic Active Radiation) is light that falls between 400nm (heavy in the blues) and 700nm (heavy in the reds) spectral region (better known as spectrum.) PAR light defines the type of light needed to support photosynthesis.

There are two important qualities to look at in PAR light for growing, one is the amount (what we would consider intensity) and the other is spectral light quality (which is referring to the spectrum the light is producing, often noted with spectrum graphs that you may have seen while looking at grow lights.)

PAR is quantified by Photosynthetic Photon Flux Density (PPFD,) measured in micro-mols per second (μmol/s), indicating how many photons in this spectral range fall on the plant each second.

If you’ve ever looked up grow lights of any kind, nearly all of them have some sort of information on the PAR/PPFD, usually PPFD is a coverage chart that shows the PPFD rating at certain heights and spreads of the light over a certain area of coverage.

Depending on the type of lighting and how it’s mounted, PPFD can be fairly homogenous (spreading the light out equally, giving near equal coverage in the recommended space for the size of the light,) but many lights tend to focus a high amount over the center of the light (where it beams down from the source,) then the numbers drastically lower as the light spreads out inefficiently (which is why it’s important to understand the numbers for coverage as well, especially if a vendor is claiming high PPFD numbers (which may be accurate, but you need to understand the spread correctly.)

Generally the higher the PPFD number the more intense the light is. If the light intensity is too high (by delivering too many photons whether per second or over the spread of the day) the chlorophyll pigment in the leaves gets damaged by photo oxidation (light bleaching.) This is why seedlings and young plants don’t typically need as strong/intense of lights (you don’t feed an infant a t-bone steak, right?) but instead gradually increasing the power/intensity through the life cycle of the plant. Dimmers are becoming popular on many grow lights exactly for this reason (or controlled via box/board.) There are grow lights and add-on electronics that are able to literally simulate and artificial sunrise and sunset with dimmers. Many LED grow lights use lenses, reflectors, optical diffusers, etc, to help control the spread and the beam of the light. HID lighting uses reflectors (winged, parabola, vented hoods,) to help control the spread of light.

You can find varying charts on PPFD recommendations for stages of growth, here are two examples (and you can see how close in range they are for the most part:

200-400 PPFD: Great for seedlings, clones, and mother plants.
400-600 PPFD: Great for early to late stage vegging cycles.
600-900 PPFD: Great for beginning to end of flowering cycle.

The bottom chart came from Fluence (a very well known provider of lights: )

View attachment 1150931

I'd recommend looking at numbers like these, not wall watts (which do factor in part of the equation, but the efficiency of the light and technology used does too.)

Awesome info thank you very much.

 

[Olderfart]

Forget watts, look at PAR/PPFD.

PAR (Photosynthetic Active Radiation) is light that falls between 400nm (heavy in the blues) and 700nm (heavy in the reds) spectral region (better known as spectrum.) PAR light defines the type of light needed to support photosynthesis.

There are two important qualities to look at in PAR light for growing, one is the amount (what we would consider intensity) and the other is spectral light quality (which is referring to the spectrum the light is producing, often noted with spectrum graphs that you may have seen while looking at grow lights.)

PAR is quantified by Photosynthetic Photon Flux Density (PPFD,) measured in micro-mols per second (μmol/s), indicating how many photons in this spectral range fall on the plant each second.

If you’ve ever looked up grow lights of any kind, nearly all of them have some sort of information on the PAR/PPFD, usually PPFD is a coverage chart that shows the PPFD rating at certain heights and spreads of the light over a certain area of coverage.

Depending on the type of lighting and how it’s mounted, PPFD can be fairly homogenous (spreading the light out equally, giving near equal coverage in the recommended space for the size of the light,) but many lights tend to focus a high amount over the center of the light (where it beams down from the source,) then the numbers drastically lower as the light spreads out inefficiently (which is why it’s important to understand the numbers for coverage as well, especially if a vendor is claiming high PPFD numbers (which may be accurate, but you need to understand the spread correctly.)

Generally the higher the PPFD number the more intense the light is. If the light intensity is too high (by delivering too many photons whether per second or over the spread of the day) the chlorophyll pigment in the leaves gets damaged by photo oxidation (light bleaching.) This is why seedlings and young plants don’t typically need as strong/intense of lights (you don’t feed an infant a t-bone steak, right?) but instead gradually increasing the power/intensity through the life cycle of the plant. Dimmers are becoming popular on many grow lights exactly for this reason (or controlled via box/board.) There are grow lights and add-on electronics that are able to literally simulate and artificial sunrise and sunset with dimmers. Many LED grow lights use lenses, reflectors, optical diffusers, etc, to help control the spread and the beam of the light. HID lighting uses reflectors (winged, parabola, vented hoods,) to help control the spread of light.

You can find varying charts on PPFD recommendations for stages of growth, here are two examples (and you can see how close in range they are for the most part:

200-400 PPFD: Great for seedlings, clones, and mother plants.
400-600 PPFD: Great for early to late stage vegging cycles.
600-900 PPFD: Great for beginning to end of flowering cycle.

The bottom chart came from Fluence (a very well known provider of lights: )

View attachment 1150931

I'd recommend looking at numbers like these, not wall watts (which do factor in part of the equation, but the efficiency of the light and technology used does too.)

Alas, us DIY types are stuck with learning the hard way, from the plants themselves. Wish I had a PAR meter, but it ain't gonna hoppen at the price. I think I learned a bit about my lights on the current grow. Good news is that they are more than strong enough. Bad news is that they are more than strong enough to cause problems...

 

[Sour D]

Alas, us DIY types are stuck with learning the hard way, from the plants themselves. Wish I had a PAR meter, but it ain't gonna hoppen at the price. I think I learned a bit about my lights on the current grow. Good news is that they are more than strong enough. Bad news is that they are more than strong enough to cause problems...

They have phone apps. Probably about as accurate as cheap ph meters