New Grower Stupid question

[diskokobaja]

i got one really stupid question, i was thinking if autoF. dont need 12/12 for flowering, can they be grown under the bloom light only??

 

[blue]

And you're right!

Not a stupid question at all! An auto can grow from start to finish under either the bloom or veg spectrum.
Some would argue that in a MH vs HPS for autoflower - the HPS would win if you could only choose one. (Scientists ...)

I've got an article somewhere if you're interested

 

[blue]

Here's the science talk (from Mitchigan State Univeristy)

I was just answering a question about swapping over MH to HPS and stumble accross this. It's a MH vs HPS thread explaining why HPS is possibly better start to finish on all canna)

Metal halide vs. high-pressure sodium: An age-old question for cannabis growers By Greg James
​

While the technology behind indoor plant lighting has evolved rapidly, one thing has stayed fairly constant: Most growers still prefer to use high-intensity discharge lights in their grow rooms.

The HID lights that are most frequently used in growing plants indoors and in greenhouses are metal halides and high-pressure sodium (HPS). The reason both are commonly found in grow rooms – especially marijuana grow rooms – is because there has been a long-standing belief that metal halides are best for the early vegetative stages of growth, and HPS are more effective for flowering. So is there any truth to this?

Will metal halides lead to bigger, bushier, more robust plants, and are HPS bulbs the right way to go for flowering and bigger buds?

To get the answer, I did some research and decided the best place to find information on the efficacy of different types of supplemental lighting would be university studies.

Several major universities have done extensive research on plants grown indoors and in greenhouses. Utah State University and Michigan State University both have a wealth of information and studies on HID lights.

The university studies reveal there is no evidence to support the commonly-held belief that the extra blue light from a metal halide is best for vegetative growth. However, HPS is considerably more efficient for photosynthetic radiation (PAR) than metal halides.
And, careful university research has shown that the amount of light plants receive affects growth more than anything else.

At Utah State University, Professor Bruce Bugbee recently published a paper on the subject, and his research on a variety of lights and manufacturers demonstrates that (A) HPS puts out considerably more photons per watt of input power than metal halides, and (B) that there is no evidence to support the assertion that increased blue in a metal halide leads to more vegetative growth than HPS.

When I asked Professor Bugbee if the increased blue spectrum in metal halides led to bigger plants in the early grow stages, his answer was straightforward: “There is no theoretical or empirical evidence to support that claim. The apparent MH effect is likely caused by the amount of light, rather than the color of light.”

This latter point is important because so many in the marijuana industry buy metal halides for early stage “veg” growth, and switch to HPS for bud. However, if you trust the validity of carefully conducted, unbiased university studies using accepted scientific methods, then purchasing metal halides for “veg” may be a waste of money, and could lead to decreased yields.

Some points to ponder from my discussions with two university professors (Professor Bugbee at Utah State and Erik Runkle at Michigan State) who have studied horticulture and supplemental lighting for many years:

• HPS is about twice as electrically efficient as metal halide.
• Photosynthetically Active Radiation (PAR) is what really matters to plant growth, and delivery of usable PAR is better with HPS than metal halide.
• The enhanced blue in metal halide does not lead to increased plant growth compared to HPS in the “veg” stage.
• Metal halides deliver, on average, about 80,000-110,000 lumens per standard 1,000-watt bulb. For the same wattage, HPS bulbs delivers about 130,000-155,000 lumens. This increased light output far outweighs other considerations when trying to maximize plant growth indoors under electric light.

 

[autogogo]

Here's the science talk (from Mitchigan State Univeristy)

Metal halide vs. high-pressure sodium: An age-old question for cannabis growers By Greg James
​

While the technology behind indoor plant lighting has evolved rapidly, one thing has stayed fairly constant: Most growers still prefer to use high-intensity discharge lights in their grow rooms.

The HID lights that are most frequently used in growing plants indoors and in greenhouses are metal halides and high-pressure sodium (HPS). The reason both are commonly found in grow rooms – especially marijuana grow rooms – is because there has been a long-standing belief that metal halides are best for the early vegetative stages of growth, and HPS are more effective for flowering. So is there any truth to this?

Will metal halides lead to bigger, bushier, more robust plants, and are HPS bulbs the right way to go for flowering and bigger buds?

To get the answer, I did some research and decided the best place to find information on the efficacy of different types of supplemental lighting would be university studies.

Several major universities have done extensive research on plants grown indoors and in greenhouses. Utah State University and Michigan State University both have a wealth of information and studies on HID lights.

The university studies reveal there is no evidence to support the commonly-held belief that the extra blue light from a metal halide is best for vegetative growth. However, HPS is considerably more efficient for photosynthetic radiation (PAR) than metal halides.
And, careful university research has shown that the amount of light plants receive affects growth more than anything else.

At Utah State University, Professor Bruce Bugbee recently published a paper on the subject, and his research on a variety of lights and manufacturers demonstrates that (A) HPS puts out considerably more photons per watt of input power than metal halides, and (B) that there is no evidence to support the assertion that increased blue in a metal halide leads to more vegetative growth than HPS.

When I asked Professor Bugbee if the increased blue spectrum in metal halides led to bigger plants in the early grow stages, his answer was straightforward: “There is no theoretical or empirical evidence to support that claim. The apparent MH effect is likely caused by the amount of light, rather than the color of light.”

This latter point is important because so many in the marijuana industry buy metal halides for early stage “veg” growth, and switch to HPS for bud. However, if you trust the validity of carefully conducted, unbiased university studies using accepted scientific methods, then purchasing metal halides for “veg” may be a waste of money, and could lead to decreased yields.

Some points to ponder from my discussions with two university professors (Professor Bugbee at Utah State and Erik Runkle at Michigan State) who have studied horticulture and supplemental lighting for many years:

• HPS is about twice as electrically efficient as metal halide.
• Photosynthetically Active Radiation (PAR) is what really matters to plant growth, and delivery of usable PAR is better with HPS than metal halide.
• The enhanced blue in metal halide does not lead to increased plant growth compared to HPS in the “veg” stage.
• Metal halides deliver, on average, about 80,000-110,000 lumens per standard 1,000-watt bulb. For the same wattage, HPS bulbs delivers about 130,000-155,000 lumens. This increased light output far outweighs other considerations when trying to maximize plant growth indoors under electric light.

good stuff, my first light was sold as an 800w dual spectrum. Paid almost $$$ (who remembers...more than $400) and now looking back it was just a 400w mh and a 400w hps mounted in one reflector. And if I was starting out with autos and hid I might do it all over again. I ordered a bloom cycle led and sent it back. Until further notice I guess I'm a full spectrum for autos guy. At least until I can figure out definitively when they stop vegging and start flowering. Mine are doing everything all at once all the time.

 

[blue]

Yeah - Full spectrum for me too! One light ... to Rule them All!!
Although if i did "NEED" to use either MH or HPS .. i'd go for an HPS with extended blue spectrum (sylvania). But so much wasted heat energy!

I use an LED light - i just put it on start to finish and seems to do the job pretty well so far! No complaints!

 

[diskokobaja]

I have switched to led because of heat,but i start with dual hps, and got great results.. i was wondering could autos been grown under the only red spectrum..

 

[blue]

I'm not 100% sure to be honest - but if it's your only option, i'd definately give it a go - the university hypothesis above does seem to suggest that with enough light intensity, the HPS (which is typically 2700k (red...well orange)) would work.

My only concern would be that HPS bulbs do have a wider spectrum than tailored wavelengths of LED

I think we need to call in the advice of someone who knows for sure

(I'll find someone)


@arty zan - You know you're LEDs ... is this a question you're comfortable answering? ^_^

 

[diskokobaja]

i have blue and red colors in my led, this was just a thouth, could it be grown with only bloom spectrum,hps or led doesnt matter..

 

[AutoWonders]

For a couple years I utilized two of Calif Light Works bloomer lights. They performed quite well. As soon as I planted germed seeds, those lights ran constantly to harvest.

 

[Joe383]

I only use an HPS for auto or photos. I have used a MH and still have the bulb but its a 7,200K bulb and believe it is too blue for growing as most MH bulb are in the 5,000+ range. I don't have any experience with the MH bulbs but know you can use one spectrum for both stages if you want.