my philosophy is to keep things as simple as possible....toward that end, i use simple plant/aquarium fluorescents in the least expensive fixtures i can find, and have always had very good results with all sorts of plants: annual and perennial flowers and ornamentals, herbs, and vegetables...the most important ingredient is your own common plant sense and your green thumb....it's easy to get caught up in the equipment and lose sight of the reason you're doing it to begin with....i am also a musician, and have seen this same condition consume many players...we call it G.A.S. (Gear Accumulation Syndrome)...it's where the stuff you use to make the music starts to take precedence over the music itself....do you really need a dozen guitars?....no....you need one....anyway, you get the idea....

good growing, and blessings to you and yours,

doug

Hi Doug,
This form has misbehaved a couple of times. I hope this third or fourth attempt is successful and that the others don't show up in garbled or worse shape.
LOL, growing under lights must require reasonable knowledge of many things and maybe a 'collection' (GAS as you call it) is a trap. I would not start a long term project without knowing and satisfying at least a few up front parameters. Although much is available on this forum and other places, it seems values for lighting specific plants must be 'secret' as such are seldom published, yet I believe adequate lighting must be one of the the more important considerations for "growing under lights."

I don't think the values are secret, but there is no simple and widely accepted categorisation of plants' light requirements. You will find one or two attempts at definitions on the internet, along the lines of: full sun, high light, medium light, low light, but they are inevitably a little vague. The exact levels of light which produce good growth depend on temperature, soil ventilation, water, and fertiliser, as well as on the number of hours the lights are used. Here is one simple list that may help you out. Here is HGTV's ideas, as you can see not quite the same but in the ballpark.

I firmly believe that once you know how much light you want, which is just the light intensity you need and the area you need to cover, then picking a system to provide the light is fairly clearcut. And I'll give you a hint: it won't be "plant/aquarium fluorescents in the least expensive fixtures" ;)

Hi Shrubs -

glad to meet you. I read your input to the lengthy thread - For reference: Footcandle measurements for a two-bulb T8 fixture. I was hungry for that, and for other details. After noting that PARD is usually shown as a horizontal rectangle, between the wavelengths at which it is functional, and usually at a very low percent of natural light, I knew I was missing something important. Veggies grow well from the equator to well into the northern latitudes, and light does vary greatly over that wide spread. Soil and air temperature (and plant 'genes' that read calendars) must be the limiting factors that inhibit year round gardening because the light seems (per calculations) to be quite sufficient in most places, year round, if 2,500 to 5,000 or so foot-candles is adequate for good growing and fruting. And thank goodness that is adequate. After looking at lumens out of various lamps I was apprehensive about the cost of hardware and the electric bill involved for growing under lights. What with full sunight ringing in at 80 or 90K lumens, and veggies loving "full sun" I knew there was a catch of some kind in the amount they actually require.

It seems that the critical wavelengths for stirring up the chlorophyl are approaching rather firm definition, but they may vary with different plants. And there is the business of the non-chlorophyl stuff needing some excitation, and that excitation being different from what the chlorphyl requires.

I read the "bean" thing and other articles - so will concentrate on finding light sources that satisfy the peak needs and which emit a broad spectrum to fill in the 'undefined' needs. I noted that most information on this topic is controlled under membership and organization auspices - probably has a lot to do with hybrid stuff that the big 'ag' people do to get best yields.

I've spec'd commercial lighting. Putting the light where I wanted it for that shouldn't much different than keeping it corralled and distributing it on a plant; however, after looking for lumenaires to do that, I realize they are scarce or hard to qualify, and there is a problem or need to achieve apparent diffusion, because sunlight of sufficient intensity makes its way off of other foliage and other objects and does nearly evenly illuminate a plant.

HID MH and HPS are expensive. So are fluorescent fixtures in any number -- and there must surely be a number of them in most indoor gardens. You and your colleagues did a nice job of debunking the fluorescent topic without becoming emotinally argumentative. I hope John_Z publishes the values he collected for all the phosphor combinations.

Thank you for the links. Until I checked those, I had only a "3,500 foot-candles" comment concerning the light needed on Florida Tomatoes in extended cloudy periods. That too, of course, is way - far away - from the intensity of natural sunlight. So with the information you believe is reasonable, I should be assured my effort will not be a total waste on first go-round for lack of light - if the other large number of parameters get any reasonable attention at all.

Plant growth is limited by different factors in different locations. Sometimes water, sometimes nutrients, and more often than you might think by light. In latitudes far from the equator (England!), cloudy climates (England!), and for understory plants, major adaptations are made to utilise available light most efficiently.

When looking for light intensity from your lights, remember that relatively few plants can utilise light above a certain level, usually a lot less than 10,000fc, and that noon sunlight occurs only at ... well, noon! Natural light varies from that 10,000fc or so level at noon down to a tenth or less in early morning or late afternoon. You can maintain your artifical light at full intensity for 16 hours. It is certainly a challenge to achieve noon sunlight levels with artificial lights, but luckily it is unnecessary. But still the levels needed for most plants are far far above normal domestic lighting and correspondingly can be expensive to run.

The wavelength usage of plants should not be a confusing issue. The actual rates of metabolism of different organisms with different wavelngths of light (including plankton, corals, and numerous plant species) are well documented. Confusion has arisen because the absorption spectrum of chlorophyll has been promoted, for various good and bad reasons, as being the ideal spectrum for plants. It isn't! The ideal spectrum for plants varies greatly, but a rough approximation has two peaks in the red and blue, with a lower green region but the green region is only 40%-90% of the level of the red and blue peaks, thus green light is at worst 40%-90% as effective as red or blue light, not virtually useless as the plant light sellers would have you believe. Additionally, as you suggest, other wavelengths have uses beyond immediate photosynthesis. And, as I mentioned before, a growing enclosure can reflect back the green light multiple times until it eventually gets used for photosynthesis, increasing its usefullness further.

After looking at the spectral data published by the major lamp manufacturers, it may be a bit difficult to match lamps to the need. I'm hoping garden veggies all want to see about the same kind of light.

Its keen that you emphasized the green light reflecting from the foliage - it might have been a long while before the realization that whatever I see is reflected light. I expect to see a lot of green - and now to reflect it back to the growth.

I believe forum readers hope a thread isn't too different between beginning and last comment, but how can a newbie ask about things that come up in a response without sort of splintering things?

For instance, what are the nanometers of the color bands that are right for veggies?

And, isn't selecting a culivar for 'growing under the lights' probably best accomplished by picking from a list of recommended cultivars and discussing them with others?

Is there a good reference that is suggested reading for most aspects of indoor gardening? I'm primarily interested in garden veggies, plants for landscaping, and flower beds -and it is pleasant to have two or three flowering specimen inside the house.

And 'Thank You!' for the several responses and thoughtful comments.

...picking a system to provide the light is fairly clearcut. And I'll give you a hint: it won't be "plant/aquarium fluorescents in the least expensive fixtures" ;) -- said shrubs_n_bulbs

The information supplied on the forum was enough for 'partial familiarization'. After noting the large candlepower required for vegetables under lights, the next thing was to make a sketch and discover what could be done with the better fluorescents. Ouch! When needs approach 5,000 candlepower, not much may be accomplished with fluorescents as the the primary light source. They probabably have a place in illuminating the understory as you called it. So HID lamps are stacked on the learning curve. They are expected to be "in" as the primary light source -- and on the shopping list.

A couple of 'crops' are already eliminated from the plans because of the extra-ordinary up front costs and the ongoing expense of growing vegetables under lights.

I don't grow veggies so I'm not the best to advise for them. I know that leafy vegetables like lettuce do grow fine at more like 2,000fc. I think things like Tomatoes and Peppers want the really strong light. Again I can't give specific advice on spectrum for vegetables but the standard advice is to start out with sufficient blue spectrum to produce strong compact growth, meaning metal halide, fluorescents such as 4100K, or HPS with supplemental blue light (which might be natural light). Then use HPS later in the season for flowering and fruiting, because the spectrum is suitable and the light output is better than anything else available.

As for fluorescents not achieving 5,000fc. That is possible but is certainly at the high end of what you can achieve. You'd need to be looking at compact fluorescents (T4/T5), T5 straight tubes, or HO/VHO/overdriven T8/T12 tubes. And you'd have to pretty much cover the growing area with tubes and you'd have to pick or design the fittings carefully so that the tubes are spaced apart too much.

Lettuce, radishes, bunching onions (along with Tomatoes, Peppers, Basil, and more) have a place in the plan, so it would be nice if those would do well under a couple of thousand foot-candles. The other topic areas of the forum don't seem to offer more guidance on light requirements than what you gave.

One might go astray in thinking of higher and lower forms of plant life, especially if not a botanist or horticulturist.

Flourescents may be OK for lower forms, LOL, meaning to me, plants that grow no more than 6 or 12 inches tall, with a single canopy of leaves, such as a melon on the ground, or cuke on the ground instead of allowed to climb.

Although ballasts have long been a profit center, there must be a world-wide shortage of ballast manufacturers for HID lamps - otherwise ballast prices would not be so outrageous. It doesn't seem it could require a $200 to $400 product to regulate a few amps at low voltage. Maybe one may realistically expect those to last for a long time, so once over that hurdle, no need to face all of it again - at one time. Any comment on that?

If it is not a violation of the forum's terms, does anyone have a good supply line for remotely mountable ballasts, HID lamps, lumenaires or mountable lamp sockets and reflectors?

At the expense of looking silly, I am indeed talking to myself. Someone wrote, 'lighthouses' for navigation and a couple of other 'light' things don't obey the inverse square law, which inexpensive lights must.

Imagine a 1000 watt brand name lamp sparkling like a crystal: HID, MH type, with a shiny reflector and a custom black lumenaire (trimmed with looks like chrome); sporting a gentle giant remote electronic ballast, of course! What is left of it after spacing it 6 feet from the nearest plant? Could it be several hundred bucks for less than 10,000 lumens - effective - and can that small count top two digits when spread over 64 square feet at top of crop?

1,000W of HID produces roughly 100,000 lumens. What is left of it after six feet or six hundred feet is ... 100,000 lumens! It doesn't magically disappear into the air, it just spreads out. You should control how much it spreads out, and in which directions, using a suitable combination of reflectors and white/shiny baffles so that as much as possible of the 100,000 lumens arrives at your plants, however far away they might be.

100,000 lumens over 64sf comes to about 1,500 foot-candles if you do it well. In practice there will always be some loss of light either sneaking off in the wrong direction or from the small losses at each reflection. Expect to get no more than 80% of the light onto the plants, and in practice expect to have a brighter area near the centre of your lit crop, with dimmer areas around the edges. A bright white surface sends 80%-90% of the light back evenly in all directions, and a clean shiny metal surface can reflect 90% or more but mostly in one direction. Metal reflectors should be carefully shaped but slightly uneven, you aren't trying to burn a hole in the plant! White baffles should enclose the lit area as much as possible because the bounce the light back in all directions rather than focussing it in one direction.