G.W.

To anyone reading this please forgive my disjointed and inarticulate and junk sciency post which I'm currently editing so as to not sound completely ignorant.
This post will be chock full in a few minutes or.maybe I can delete the whole Damn thing and copypaste to a draft.....
In other words, I know what I know but this does not help you unless I back it up with science.
My short answer is increased red light.

Now about color temps.
On its face this seems like an obvious thing.
I was just looking at Richard's recommendations elsewhere that 6500k is preferable for most (sorry to paraphrase you Richard) plant growth.

One thing to understand here is that there are different ways of defining the conversion of electricity into light.
Namely that a bulb can produce most of its energy in the spectrum visible to the human eye, or in he case of incan lighting mostly outside the visible spectrum, infrared specifically.
Luminous flux (visible) and radiant flux (absolute)

plants aren't people and have their own photosynthetic response range completely independent of how much the light stimulates our eyes.
This makes the standard means of defining light output considerably less usefull and this decoupling from human perception complicates understanding how efficient a light is for plant growth.

A prime example is green light.
The human eye is extremely sensitive to green light and so green light sources with lux numbers that would be laughable for a white light source are intense or blinding.
Since plants reflect green light I'm sure you can guess how well they utilize pure green.

I'll be back later with some actual science and maybe in the meantime someone else like Richard (who is probably more educated than I'll ever be) can fill in the blanks or reeducate me if I'm talking smack.

Here are.some links
Photosynthetically active radiation - Wikipedia, the free encyclopedia
http://en.m.wikipedia.org/wiki/Lumen_(unit)
Photosynthesis, Maximized.

Dang....this post is gonna stay messy and I'll make the next one hawt.

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winter winners, jackfruit, carambola, hua moa, d namwah, hak ip lychee with pink leaves 2 days before a cold snap eeeek!

Winter losers, kohala longan, misi luki, 80% jackfruit seedling loss

first bloomers, HUA MOA, DC, D NAMWAH, FHIA 17, KANADARIAN, RAJA PURI, M D NAMWAH

best bunch FHIA 17 , undisclosed

WORST BUNCH hua moa, 2 fingers

Richard

I have recommended 6500k for certain crops. Definitely not all - nor even most plants.

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G.W.

Thanks for correcting me and sorry to put words in your mouth.

Now since my self education has neglected the area of the banana's specific photosynthetic response range......
Maybe after work today I'll find some time to fill in the blanks for everyone right after I fill them in for myself.

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winter winners, jackfruit, carambola, hua moa, d namwah, hak ip lychee with pink leaves 2 days before a cold snap eeeek!

Winter losers, kohala longan, misi luki, 80% jackfruit seedling loss

first bloomers, HUA MOA, DC, D NAMWAH, FHIA 17, KANADARIAN, RAJA PURI, M D NAMWAH

best bunch FHIA 17 , undisclosed

WORST BUNCH hua moa, 2 fingers

Viper1436

I bought the 1000w apollo grow light, we shall see how it goes.

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Richard

Here's a picture of the Apollo 1000w MH spectral density. For plants, you can see that it is an improvement over HPS but on the either hand, the bulb is clearly designed for human vision. About 1/3 of your electric bill will go to energy the plant simply doesn't use. On the plus side, you'll be able to see them just fine!

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redswe

A chart that may help explain what Richard is saying...




This also shows why using lumens is not always the best choice to determine lamp selection. A bulb represented by the top chart would probably have a higher lumen output than the bottom chart.

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Howard007

Metal halide bulbs were the gold standard and virtually the only choice for keeping high PAR requiring hard corals alive in reef tanks for many years. They are still popular and widely used because they have the ability to punch through deeper water tanks (over 30" deep) more effectively than T5's and LED's PAR tests have shown. The thing I don't like about MH lighting is that being a point source light it was shown that it gives off very high PAR output focused within a small area and then drops off significantly as you fan out, whereas T5 HO and various LED clusters didn't have the same punch at depth however were far more uniform in giving similar PAR values over a large underwater landscape.

Because of this, it seems like MH would not be the ideal cost effective setup for use as plant lighting in a small scale residential setting as opposed to using rows of T5 HO bulbs with correct individual reflectors or some of the newer generation LED panels.

Anyone??

Richard

I can understand the use of purpose-built LED systems for tropical plants from the forest floor or for factory production of leafy greens. For fruit or bud production, it is not possible to obtain the necessary energy density with LEDs. The T5 HO 6500k are the bulb of choice for this task in commercial agriculture.

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