Lumen requirements for bougs, ficus, and olives?

daniel

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Anyone know or have a good link with the info? Or, is there a "safe" level? I'm looking into a T5 set up with 20,000 lumen, which I think is more than enough. I'd really like to have good growth over the winter in my tropicals, if I could. Anyone have any good recommendations that have a lot of tropicals? Will? Anyone else?
 

daniel

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I did--nothing gave specific requirements, hence why I asked here.
 

Bonsai Nut

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There is a complicated scientific answer, and an easy practical answer.

The scientific answer involves the light requirements of the tree species, and the spectral intensities of the bulbs you select, as well as the distance from tree to bulb and the photo period. Just because you are using T5's with 20,000 lumens does not mean you'll be successful. Bougs and olives are high light trees, while ficuses will be easier.

Direct sunlight is 32,000 lumens or more of full spectrum pure "white" light (in the tropics at noon it can easily exceed 100,000 lumens). All artificial light will have various spectral intensities depending on how the light is generated. While white light may be the most appealing or natural-looking to our eyes, the light needs of our trees are very different. Chlorophyll absorbs light in the blue and red spectra, but not much in the green spectra, which is why our bonsai appear green to us - they are reflecting all the green light out of the full spectrum daylight. Therefore you are looking for a specific type of artificial light that peaks around 475 nanometers (nm) with a second peak around 675 nm. It is not enough to have 20,000 lumens of "light" - but rather the equivalent of 20,000 (or more) lumens of light at 475 nm and 675 nm. This is light that is available for photosynthesis, and many bulbs created for gardening purposes will use the term "PAR" (which stands for Photosynthesis Available Radiation) as an indicator of how much of the light they generate is usable for photosynthesis in plants.



There are two ways to go about satisfying the demand for PAR - one is to get a broad spectrum light of high intensity knowing that your plants will take the light they need, while the other is to combine two types of narrow spectrum lights to give your plants only the light they require. An example of the first would be to use low temperature (4500K) metal halide lights that will look yellow-white to the eye. An example of the second would be to combine a very blue (20,000K) metal halide bulb with a very yellow/red high pressure sodium bulb. The first approach may be easier, but the second will likely provide better results for the same amount of electricity - since a greater percentage of the light being generated is usable by your trees.

Once you have the suitable light sources, you need to take into account several more factors. First, light diminishes with the square of distance, so the closer you can locate your trees to the bulbs, the better (of course HID lights generate significant heat so you need to make sure you don't burn up your plants). Second, you need to offer decent photo period of at least 12 hours per day (there have been lots of studies about how changing photo period will affect plant growth that you can check out - just know that 100% light is NOT a good thing and won't make your plants grow twice as fast). Third, you need to check the age of your bulbs - many bulbs will start to diminish in intensity almost from the moment you start using them, with many losing 50% or more of their intensity with 12-18 months of use (check with the manufacturer).

Additionally, static lights cause shadows on trees - with the unfortunate consequence that higher leaves will grow while lower ones will die. This is less of an issue with "bar" lights sources like flourescents than with point light sources like HIDs. For large indoor growing setups with HID's, many growers use light rails to move their lights back and forth, allowing greater coverage over more plants, and generating much thicker, lusher growth.

So that is the intro to the science part :)

As far as the practical part goes, some people just stick their trees under cool white flourescents and call it a day. For low light tropicals - ficus, magnolia, schefflera, fukien tea - this will be ok if you have new bulbs and you keep your trees within 12" of the bulbs. I wouldn't try this with high light tropicals like bougs or olives, and don't even THINK about pines.

Oh - and the best source for lighting info is going to be professional hydroponic sites (versus anything specific to bonsai).
 

milehigh_7

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whooo hooo you go BNut!!! Good offering! Good explanations.
 

C.A. Young

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Indoor Lighting

Bnut is right on the money. However, as someone who has used artificial indoor lighting for years, I can offer some practical advice. My guess is that if you're using T5's, they're probably sunblaster or a similar product. The most common of these uses 6400k bulbs, which are perfect for bonsai. The only problem is that any tree taller than 12 or so inches will receive significantly less light on their bottom branches if you set all your lights up over head. So, assuming you have four lights, why not set three up over head, and one behind. Then rotate your trees once a week. As for which species will thrive under these conditions, ficus, serrissa, fukien tea and sageretia will be perfectly happy, and will put on decent growth. Olives, on the other hand, will sulk all winter.

My personal view is that if you want to grow high light species indoors, you should opt for a good halide light system and a bulb that puts out approx. 6400K.

As for consulting a hydroponics site, I quite agree with Bnut. They are a veritable wealth of information about indoor lighting.
 
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