Also as a side note, I would particularly like to grow some orchids on the table.

I have no idea how to tell. I have tomatoes growing under 4 foot shop lights. Seems to have flowers but only one or two fruits. Found a clamp on reading light and put a large CFL warm type bulb next to them. Will see if that helps.
KennyP

Except for extreme cases, it doesn't matter much what kind of fluoresect tubes you use. Read this:

You can measure lighting sort of like you do rainfall - how hard it is raining or how much rain you get. For the most part, plants are going to care mostly about the total accumulation of light in a day.

Tomatoes, hot peppers and similar veggies need a particular amount of light in 24-hour period to be productive. That amount is generally believed to be at least 10 hours of light that has an intensity of 3,500 foot candles for cool-white fluros. (2800 FC if you are running the lights for 16 hours)

Less than this results in blossom drop or lack of blossom formation.

Mike

Mike, I think you answered my problem. Not enough foot candles -hours. In a day. Way short of 35000 fch. If we can simplify it to foot candles-hours per day.
KennyP

Kenny,

The data comes from people who specialize in growing plants in a greenhouse. IME, it is spot-on. Two years ago, I tried a couple of plants in a grow chamber that had two 105-watt CFL bulbs - 13,000 lumens at the canopy. Got dozens and dozens of blooms but I think a grand total of two tomatoes, and they never ripened. In my GH this year, I had several plants that had bunches of blooms and they were setting fruit - until the dark days of winter set in and the total of FC hours dropped tremendously. Only a couple of new maters, next to no blooms and the toms that were already set have grown extremely slowly.

In the past week or so, the sun has reappeared for a few hours each day, and I am getting a bunch of new blooms and several tomatoes are ripening and the others growing.

The amount of sunlight (called Daily Light Integral) needed is an ironclad rule. You can get by with less than 18 mols a day (~26,500 FC of sunlight, 35,000 from fluros) but you will have far fewer blooms set fruit.

Mike

***The amount of sunlight (called Daily Light Integral) needed is an ironclad rule. You can get by with less than 18 mols a day (~26,500 FC of sunlight, 35,000 from fluros) but you will have far fewer blooms set fruit.***

These are the simplified opinions and numbers I have needed. I have a light meter, but moles and lumens kinda leave me behind.
Could you give me a figure off hand of daily light hours I need to grow usable lettuce, or such green stuff as basil, inside? Probably not as critical as tomatoes.
KennyP

Kenny,

I don't have numbers for lettuce or basil, per se, but I know lettuce does not require near as much light I grow it under a sheet in summer. Basil is going to be close to sweet peppers - about 12-16 mols per day.

Here's an easy way to find out how many mols per day you are getting.

Take your light meter and measure the lux. Divide that by 10.76 to give you foot candles. Depending on the type of light, use one of these values to multiply the FC by:
Sunlight - .000718
Metal Halide - .000546
HPS - .000479
Cool-white Fluro - .000524

Take that answer times the number of hours per day the lights are on and you will have the mols/day figure.

For instance, your light meter reads 40,000 lux, that translates into 3717 FC. Since you are using the fluros, multiply 3717 by .000524, giving you 1.95 mols per hour. So if you need 18 mols/day, divide 18 by 1.95 and you need about 9.5 hours of light.

HTH,

Mike

I suppose that is standard green house knowledge, but it is new to me. You are very good at keeping it simple with out messing me up. Thank you, thank you.
I have printed it out.
KennyP

Kenny,

New to you? Five months ago, I would have thought mols/day meant how many creatures your traps caught every 24 hours!

Mike

-Blue light spectrum for Vegetative growth.(leafy)

Where is the scientific evidence? I have experimented with blue fluorescent and other people have experimented with blue LED. Vegetative growth was poor.

I have a Red Delicious tomato plant that was transplanted on Dec. 26 growing under a 105 watt CFL from 1000bulbs.com. It's a 4.1K bulb and I have never seen tighter internodal distance or distance between leaves on branches in my life. In fairness, I'm using this one light (rated at 6,900 lumens) for just that plant and am keeping it no more than 2" from the leaves.

It does lead credence to the idea that MH bulbs, known for their higher ratio of blue/red light, promotes vegetation rather than vertical growth as the important data (Quanta of light in the PAR range, moles/day and energy in the PAR range) are identical or similar for both lights.

However, I have yet to see any evidence, and can even say I have evidence to the contrary, that single spectrum blue light (as from an LED panel) contributes to a denser, shorter plant. Seedling grow much quicker, but the internodal length is longer (much like adding far-red light), though the foliage is larger.

Mike

blue light (as from an LED panel) ... Seedling grow much quicker, but the internodal length is longer (much like adding far-red light), though the foliage is larger.

What evidence have you seen?

Three different tests, done in summer, spring and winter, using LED panels I have.

The best LED panel I have used, that produced great foliage and growth, with a short internodal distance was from the first panel I bought, a few years ago. It was a red/blue panel, 14 watts, but both the blue and red lights were "lighter" in color - not a deep red or blue.

I am thinking about using some incandescent bulbs to germinate some banana seeds - that seems to be the only thing far-red light is good for.

Mike

Three different tests, done in summer, spring and winter, using LED panels I have.

Am I supposed to assume that at least one of these tests was with a pure blue LED panel? - because I don't assume.

One all red, one all blue, one mixed.

Mike

One all red, one all blue, one mixed.

Thanks. Can you name the brand and model of the all blue panel so I can look up the specs and maybe buy one?

I'll try, but I bought it from a lady who I met from buying other lights from her on e-bay.

I wish I had a light meter that measured the specific wavelength so I could at least provide that. But I suspect people are still selling similar panels. Fourteen watts, I think it has 225 bulbs.

Mike

This is great info everybody, thank you so much!

But I suspect people are still selling similar panels.

Thanks. Does it look like this one? Its peak wavelength is 465 nm whereas Westinghouse Special Blue fluorescent is 445 nm and Sylvania Super Diazo Blue fluorescent is 405 nm. Both produced smaller than normal leaves, but, frankly, I don't remember what kind of plants I tested because those experiments were conducted about 30 years ago.

Well, $42 is cheap enough. In the late spring, I can conduct new tests on tomato seedlings using these three blue light sources. (I have to wait until my basement is warm enough. Normally, I start seedlings in my greenhouse around April 1 and plant outside around May 25. My greenhouse is unused the rest of the year.)

I found one on e-bay that looks very similar to mine and the blue is 460 nm. I doubt there is much difference.

FWIW, I'm becoming convinced that lack of nuits (or just a minimum amount of something that is low in N) and lower temps (50s or 60s) will make for a much bushier, shorter plant. Likewise, too many people are paying attention to just lights, especially in the area of growing seedlings.

YMMV,

Mike

lower temps (50s or 60s) will make for a much bushier, shorter plant.

I read that higher night than day temperatures make stems shorter. (The exact opposite of the natural temperature variation.)

"I read that higher night than day temperatures make stems shorter."

ABSOLUTELY! I have never seen this discussed in this forum before, but I have printed up several research articles where this type of elongation effect was demonstrated. I found it to be 100% correct, as I experienced this myself. The greater the differential between light/dark temperatures, the greater the internodal lengths. I found this elongation effect to be much greater than any elongation effect caused by lighting.

I have at least one very excellent PDF file that has photographs of the results of various temperature experiments that illustrate this quite dramatically, but I don't recall where it came from.

Zink

This could be true but it does not apply here - the temps were always cooler of a night than during the day. On a precious few days when there was actually sunlight, the difference might have reached 20 degrees.

Mike

@struwelpeter -(Where is the scientific evidence?)

How about seventeen years of growing plants indoor, under every light imaginable. Is that enough scientific evidence for ya?

-(I have experimented with blue fluorescent and other people experimented with blue LED. Vegetative growth was poor.)

Sounds like you need to work more on growing plants and not so much on the color of lights?

It's amazing to a light gardening newbie just HOW MUCH light you really need, and how what "looks bright enough" to our eyes indoors, is really only about as bright as deep woods shade, and too little for most plants.

How about seventeen years of growing plants indoor, under every light imaginable. Is that enough scientific evidence for ya?

No.

It's not just about lights or spectra or hours of light a day, nor just about soil moisture levels or the type of ferts or the make-up of the potting mix - it's all of these factors. Plants respond to the "food" they get (light, moisture, ferts) and how well they can use them (potting mix for the roots, temps) then allocate what they produce to the part of itself that it perceives needs it - they have a self-survival motive. That might mean growing taller to intercept more light, growing more lateral shoots with smaller but thicker leaves, producing flowers that may or may not convert to fruits or seeds. Under normal conditions, nature regulates this but when people start growing indoors, they tend to not see the forest because of all the trees!

Visit the Container Gardening section and it's all about the potting mix. In this section, it's about lighting, in Growing from Seed it's temps and moisture and in the Sq. Ft. Section it's about spacing.

In other words, it's like the person who wants the ideal body and to attain it insists on following the idea diet. Not bad but without ideal drinks, an ideal exercise routine, the correct amount of sleep and living in an ideal environment, the goal is impossible to reach.

OK, time for me to wash my soapbox!

Mike