Germinating under HIDs

panhead said:

Thanks,ill pm you a few questions i have tomorrow,right now im kinda vegged out

I dont have the dual bulb lights in the single reflector like you have,i never saw them before,sweet looking

What i have is a 6 light system in this room,3 400 watt hps & 3 400 watt mh, set in 3 rows of 2 lights each row, while staggering the mh & hps each row.

The other room has 2 1,000 watt hps & 1 400 watt hps so the lighting is not excact but im hoping its close enough where i'll get an idea of any difference at harvest.

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panhead said:

Thanks,ill pm you a few questions i have tomorrow,

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First Question:
I purchased a 400-watt metal halide (MH) lamp. The salesman told me that the lamp could be used for both vegetative and flowering. However, a fellow grower told me that the MH would be a waste of time and a high pressure sodium (HPS) lamp should be used instead. What do you think?

Second Question:
In a single-light garden is it better to use an enhanced spectrum HPS lamp such as a Son Agro 430-watt bulb as opposed to a regular HPS to emit more light in the blue spectrum?

Ed’s Response (emphasis mine) :
MH lamps contain more blue light and less red light than HPS. HPS lamps produce more total light than MH lamps and more light in the red spectrum, which is used more efficiently than blue light, powering a faster rate of photosynthesis. In addition, read light helps in flowering development.

The only reason to use an MH lamp rather than an HPS is to avoid suspicion that a weird-colored light may arouse. Using metal halide lamps in any stage of growing is a waste of time and money. More total light that is useable by the plant is produced by HPS than MH lamps, so plants grow faster using HPS lamps alone.

The plants don’t need the extra blue light offered by the Son Agro. Enhanced blue light doesn’t increase production. Although plants use blue light for photosynthesis, they use more red light. In rooms with mixed lights (MH and HPS), the plants between the two lights, which were receiving a mixture didn’t perform quite as well as the plants directly under the HPS lamps, but yielded slightly more than those under the MH. You could see the “wave effect”.

The solution to the ballast problem is to replace the MH bulb with an MH-to-HPS conversion lamp. This bulb will fit into your system and is powered by the same ballast as an MH but it emits an HPS spectrum.

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Garden Knowm said:

hey email..

I will ask ed myself.. and get back to you..

iloveyou

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email468 said:

Oh boy ... I'm really confused now....Reading marijuana horticulture literature and website grow FAQs, including the one here on RIU, I always considered the advice: MH for vegetative and HPS for flowering to be sound and accurate.

And then I read this from: “The Best of Ask Ed – Your Marijuana Questions Answered”
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What are we to make of this? Are all the grow books/magazines/FAQs wrong and Ed is right? Who do we trust as authorities and what makes them so? Besides trial and error and personal experience, which is prone to all sorts of bias and other issues, how are we to make decisions on equipping our grow rooms and advising the folks who are newer to this than me?

I really, really hate that marijuana is illegal and therefore is shrouded in myth and misinformation. More FUD than anything.

sorry for the rant -- but this kind of stuff is disturbing to me.

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Garden Knowm said:

Here are some pictures of seedlings at 23 inches from a 1000 watt HPS...

Looks good!

The light is air cooled

The seedlings were put under the light once the seeds cracked at 35 inches.... 2 days later they were put into soil and placed at 23 inches....

the pictures you are seeing are 3 days after the plants were put in soil... they look great... no signs of burning...


HOPE this helps add to the discussion..

iloveyou

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email468 said:

I think it demonstrates that 1000w HPS can be used on seedlings.
do you know the ambient temp in the room?
i see the light is air-cooled but do you know more specifics about how the room is being cooled (what kind of fan, how many fans, ac, etc.)?

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