Anyone try it? Love to hear your experience. i've been playing with the idea but not sure if it's doable.

Hello,
growlite and floodlite is something seelers use..
BTW: Did you post the same on GardenWeb Citrus forum?
I will use some facts from there, if you agree!

As given in a former thread, Light isn't light. Light is measured in Lumen, Power in Watt. So if a 1000 Watt lighthouse bulb is stronger than a 300 Watt MH Lamp, isn't a thing of Wattage, it's a question: How much light will be emitted!
So the lumen per Watt ratio is the key to understand, how much light a lamp will emit and spent to your plants.
As higher the lumens, as better for the plants, and as less the Watt as better for your money account!
so a high lumen per Watt ratio will be a good term to consider and compare lamps.

For example: A 175 MH lamp, we here in Germany call it HCI or HQI, provides a Lumen per Watt ratio of approximately 60 up to 75. A good factor, but if we compare this with a comon tube light, like the Osram T8 Tube in color 840 (Coolwhite) we also reach 75 Lumen per Watt.

sure, the MH Lamps will provide more lieght, because of more power, but it's not more effective.

So grow lites are nothing special, grow lights simply emit light in a for plant benefical spectrum, usually much blue and red parts should be measureable. That's the part of the light spectrum were photosynthesis and the chloroplast structures will work best with.
So some metal halide lights will emit a light more in yellow range, and thus be not that effective, than a less power lamp in the better spectral range.
So watch the lamp spectrum and look for good peaks in red and blue, as for tubular lamps light colors of the osram 830, 840 and the adhered 860 colors would do.
A metal halide lamp, like the Osram Powerstar with 66 Lumen per Watt, has a color of 830, so emits more light in yellow range than the 60 Lumen per Watt Osram Powerstar in Color 860, so both have the same power of 250 Watt, but the less efective 60 Lumen per Watt daylight type will be more benefical for your plants.

Now, that's the basic. Plant's do not gain for a strong light, illumination time is much more important, than power.
So if you have a high effective metal halide lamp with 175 Watt 4 hours a day on, but a less power tube with 36 Watt 10 hours a day, the light of the ten hours can outbeat the 4 hours.
And for the MH lamp we consumed 700 Watts, for the tube lamp we consumed only 360 Watts... So what's better?

It's difficult, and that's why there are light engineers, which can choose and install the right lamp at the right place for your purpose and demand.
The simple job, going on ebay, and buying a strong, powerfull lamps, is simple, but often a failure.
sure, seldom it will harm the plant, but won't lead to the goal we were seeking for!

So for you I would recommend to tell me more about, were you want to place the trres, how high those trees were and than let's see, if we can find and discuse about a lamp for those purpose!

Very good input. Very interesting.

Wow, some of us has money to burn. Unlucky for us here in Callyfornia, it costs about $0.13 per kW hour.

if we have 2 lights at 500 W, running 12 hrs each day, that would be $1.56 per day, or $47/month. We can get a very good handsome looking 15-gallon citrus tree loaded with fruits at about the same price...

But in your area, if electricity is cheap and citruses are expensive, that is another story.

Joe,
do not mind, we also pay about 9 to 23 cent per kW hour....
So it's good to watch those things....

I always prefer HID lights. - Millet

hi steve,
yes i am learning just how complicated the world of lightbulbs and light systems is!! and it really is. i know not all MH bulbs are good to use. for example, most of the floodlites i looked at had MH bulbs in the 40k range so that's not good (but i'm assuming i can replace them with the right one).

yes, i did also post to the gardenweb citrus forum.

from all my research, and that includes talking to at least a dozen citrus growers, sunlight works best, even indoors. sadly i don't get any sunlite in my apt. no one i talked to liked fluorescents unless you use a bunch of them at once. even Fourwinds who developed the improved meyer lemon tree (& who sold me my tree) doesn't like fluorescents, even tho their litterature says otherwise!! i complained to them about it & asked for another tree because mine is dieing. i told them all my research said i needed an HID. we discussed, then they finally admitted their trees don't do well with FLs!! (& they admitted they need to update their litterature). right. so i asked for another tree and a fresh start. so far, they are refusing to replace it. i think they owe me.

anyway, you do bring up an interesting point and i was wondering about it too.......what's more important? light intensity or the amount of time you expose the tree? how do you know it's the length of time? i'm not disagreeing with you i'm just wondering where you got your info.

i have a small, 2 foot high dwarf meyer lemon tree. it is just over a year old. it sits in the corner of my livingroom and gets absolutely no sunlight. thanks.

Steve is 100 percent correct, when he states that the longer duration of time that the tree is receiving the extra light, is much more beneficial than the light intensity. Citrus trees belong to the C3 group of plants. Photosynthesis production by citrus trees, maximizes at only 650 PAR, which is approximately 1/3 of full sunlight, therefore any light intensity greater than 650 PAR is wasted, as it will not cause the tree to produce additional energy (sugars). - Millet

Sorry Millet,
there is a type mismatch!
Citrus is a C3 plant, and not like corn a C4 plant. Greatest difference betwen C3 and C4 is: C3 plants have a saturisation level, C4 plants not.
And at saturisation level the plants have a balanced metabolism, so the light is now intense enough to build enough sugars for the complete biological process and no reserves are need. But as more light the plants get, as more sugar will be developend and put into reserves, like wood, roots and fruits.
The next saturisation level is higher, and first at this stage, more light is wasted....
See: Biology of Citrus, Spiegel-Roy and Goldschmidt, University of Cambridge Press

It was clearly a typo, happens to most of us. Sometimes what we think is not what gets there at the fingertips. Surely Millet meant C3 plants, as he has mentioned this several times in the past in relation to light saturation.

Thanks Joe and Steve. I corrected my post to reflect C3. It is my typo, you will find many other past posts on this forum where I mention citrus as a C3 plant. - Millet