Farle,

Being a first-time poster you get a free pass! In the future, though, if you want good answers, provide more info.

What is the power (in watts of the LED panel? How much area do you expect to cover? Do you want to use it in the future to grow seedlings or plants to maturity?

Me - except for experimenting, I tend to use plants I intend to grow under the light. A 14-watt all-blue panel works great for seedlings - worthless for a mature tomato plant.

Mike

Ok, I'll try and provide some more info regarding my rig.

At the minute, my rig consists of blue LED 'strips' that consists of 54 blue LEDs (450nm blue) with a combined mcd of 5400.

Plus, a red strip of 15 red led (660nm), 1500 mcd.

These strips 'mcd' are based on the 120 degree viewing angle covering a 10 cm by 5 cm area.

I also have a spot of 5 times 3500 mcd RED LEDs (17,500 mcd) with 30 degrees (aimed at plant focus area), which I intend to multiply when I figure out a workable design.

They're currently held 2 and a half inch above the DWC kit I bought (Airstone, plus growth nutrients) with a standard computer fan for changing the air.

Whilst I understand that, especially for whatever you want to grow, you need to use a sample of whatever you want to grow as a decider. But, as previously stated, I want to be able to see if my light is working within 1-5 days, if possible, as I really want to make sure I've got the right area before I devote more time to a project that is potentially doomed to fail.

As for the future, I'd rather make my rig work from what I've got now (A small tomato plant, with 6+ leaves) to fruiting. (Redesigns are more than acceptable, providing I know that the lights work with the plant, since adding more spots or strips to a completely new design is fine, as long as I know it is benefiting the plant)

I can also upload pictures of the rig, if that would help

A pic would help. As far as finding out in 5 days - quit! Five weeks - yeah.

Mike

Well, I don't need absolute confirmation, just an idea that what I'm doing is working rather than wasting my time.

As far for the rig itself, here is acouple pictures of it.

http://img72.imageshack.us/i/01052010044.jpg/
A full picture of the rig, including the DWC bucket.

http://img72.imageshack.us/i/01052010046.jpg/
A picture of the LEDs (Camera didn't like the light intensity, so it came out blurry).

http://img13.imageshack.us/i/01052010045.jpg/
http://img32.imageshack.us/i/01052010047.jpg/
Overview of the light enclosure, second image shows distance from light to plant ( around 2.5 inches from light to bucket, 2 from light to plant ish)

Thanks.

That's a little too impatient for me. Sounds like you're trying to push this thing w/o testing straight to market. That's what's wrong with all the products out there now.
I test lights with caladiums. If you get leaves at ground level the light is good. If the leaves are 4-5" from ground level the light is average and if the leaves are 8" or more the light is poor. The more they have to stretch the less light they're getting.
Now I know that caladiums are low light plants buy most people don't want leaves next to the ground or dragging it. It's the quickest light test I know other than a meter.

Heh, I'm not trying to push this to market (assuming you mean selling it), I'm merely tinkering (and trying to outdo my brother in growing stuff).

I'll try some caladiums. :)

Well, from your specs you will be getting about 25.5 lumens if all the bulbs are installed. If the plant is within the 50 sq. cm. area, you should be getting enough lights for seedlings but I doubt they will have enough intensity to grow a mature tomato plant.

Mike

Would you mind sharing the calculation with me and how many lumens I'd need for seed to maturity?

Not sure I can explain it but I can give you links:

mcd to lumens Enter the mcd and beam angle and you'll get the lumens

cm to inches Footcandles or light intensity are measured in sq. ft.

I presumed your lights are 1/4 of a foot from the light, so the light intensity will double twice (I think this is correct). That would give you 100 lumens per square foot but your lights are focused in ~10 square inches. That should mean about 1440 Footcandles.

YMMV,

Mike

I thought my math skills were good but I don't get your figures Mike?? By my figures he should need about 1000 of those setups to do any good.

Just read the last part of your message. First off, lumens are almost like points on the show "Who's Line Is It?" they are misleading. They count but only when put in perspective. Luminance flux, or light intensity is what matters the most. With sunlight, HPS or MH lights, one needs a Daily Light Integral of about 22 mols per day (that's the total amount of PAR light received in 24 hours) for tomatoes and peppers. A 400 watt HPS (50,000 lumens or about 4645 FC) placed a foot above the plant and running for 10 hours a day is enough. Alas, I do not have a conversion factor for LED lights.

The best I can do is if you get a light meter and tell me the readings at the top of the plant, I can tell you how it compares to mine.

If I had the knowledge to build a LED panel, I would throw in several spectrum of red and blue, plus add a few orange and white bulbs and even a handful of violet, green and yellow. Plants do better with a wide spectrum of light, not just a few wavelengths.

One of my experiments I'm doing now has a Legend tomato plant growing in a DWC system. It sits about a foot from a 125 watt R/B/O (7/1/1 ratio) but to help combat long internode length, I have a 2.8 watt white LED sitting 1/2" from the tip of the heart - and it touches several leaves. The plant is not growing quickly but rather nicely. Unlike the product of some "herb" growers, tomatoes don't fetch thousands or even hundreds of dollars per pound so keeping growing expenses down is paramount, unless it is simply for a plant and a desire to avoid buying tomatoes at the store. All lights are more effective on shorter plants with tight nodes. If this test turns out positive, I should be able to grow six plants using ~140 watts of energy per hour. It would cost me about $20 in electricity over four months but if the plants do decent provide at least 120 pounds of fruit.

YMMV,

Mike

Taz,

You may be right, though I don't see him needing 1000 of them! His set-up, according to the calculators and figures he supplied, should deliver 25 lumens. Most definitions of a lumen is the amount of photons falling on a square foot from a foot away. If his light is indeed about 3" away, that should translate into 100 lumens per sq. ft. But he is covering only .069 sq. ft. If he had the entire area covered in the same way, that would translate into 1450 FC or about 15,600 lux. Not near enough for mature plants but enough for seedlings. The problem would be keeping the plants in the 10" square area or more precisely, the 2" wide area.

Did I really screw up my math? It would not be the first time!

Mike

Unfortunally I don't have a light meter (I do have my brother's 'flashmate' meter, but it doesn't have LUX as a setting, just some ISO thing that sticks out a value of 90 something when stuck infront of a 60 watt bulb)

I'll probably stick in another 4 of the 660nm LED clusters (17,500 mcd, 30 degrees, 3.747 lumens) which will add another 15 +/- lumens as well as some of the other wavelength LEDS.

Although I am up for adding some other type of light source, but I'm not up for buying a ballast and other expensive gear for one tomato plant, but cheaper options might be.

Here's a very inexpensive light. Despite its small size, at the distance I have it from the plant - about 1/2", it delivers 30,000 lux. It has several different wavelengths reflecting on the back side of a CD (a great and easy way to see the lights).

You do need to understand that there is no "cheap" way to grow mature plants using artificial lighting. LEDs are inexpensive to operate compared to HPS, CFL and MH but not cheap to buy, though their cost is slowly dropping. Not having the knowledge to build my own LED, if I was going to try to raise a tomato plant to maturity, I would build four arrays of four 23-watt, 5000K CFL panels. Line the plant with them. The cost would be about $40 for the bulbs plus the fixtures to hold them.

But I keep playing - by 2012 I want to be raising 600 tomato plants indoors - at the same time.

Mike

Oh I get that its not a cheap way of growing when compared to a patch of dirt and some sun, but when I say 'cheap' I mean in terms of outlay (Spending 100+ isn't viable, but 30 is).

Is there another light system (Other than LEDs) that is similar to that LED bulb? (As in, a grow light that connects directly into a standard light fixure, no additional components needed)

Mike I'm not saying you screwed up your math. Maybe I did. It's been a long week and I'm tired. Got to get some long overdue rest. I was exaggerating a bit.

farle,

CFL bulbs. But even then, I suspect you will need to spend ~$50 to grow a plant. Or two plants. The thing is, most lights are not cost-effective for a single plant. Perhaps a 75-watt HPS (~$45) would work. Or a 400 watt HPS/MH combo that should grow six plants for about $170.

Taz,

I'll see your tired and raise you an exhausted! I publish a weekly newspaper, which in normal weeks is pretty much a full-time job. This past week though was a special issue which meant I needed to deliver it to a bunch of homes in the neighborhood. Between Thursday and Friday, I walked about 15 miles, carrying papers and laying them on porches. Got an up-close and personal view of all the area but good grief - I'm not use to this!

Just to say I very too easily could have made a mistake. If my former neighbor was still living behind me, I would ask him - he was actually a rocket scientist!

Mike

Having looked at CFL bulbs on the ol'e Wikipedia, I actually realise that I have several of these things lying about the house (Brother other half loves the damn things).

So for CFL, what do I need in terms of specification?

A light meter! Buy one. It will be your most useful tool! Add lights until you get to 30,000-40,000 lux to all of the plant, or at least most of it. Use the 5,000K bulbs - IME they are better than others.

YMMV,

Mike

Now, being a rather impatient guy, I want to pick a plant that reacts fast if its in good light and dies quick if it isn't.

No plant is going to die fast under a light that isn't good (with the exception of some UV lamps).

You should want a plant that is of practical importance and has an internode length that is sensitive to light quality.

In my ongoing experiment here, I found
Tomato Velvet Red to be such a plant. Is 27 days from planting seed too long for you to wait?

Wait a second, did you say 40,000 lux?

I've looked around at CFL lamps and the most powerful ones (the bulb style) clocks in at 1100 lumens, so that's 36 bulbs (lux=lumens, so 40k) (At 20 watts a bulb, that's 720 watts) which seems alittle excessive for one small plant.

Am I wrong?

Also, thanks pete, but I haven't seen any velvet red at my garden center.

Farle,

Lux and lumens are NOT the same thing. The 30-40,000 lux needed is for growing plants to maturity, not seedlings. The latter need maybe 3,000 lux.

Mike

I've looked around at CFL lamps and the most powerful ones (the bulb style) clocks in at 1100 lumens

There are 105w CFLs that put out 7,150 lumens.
http://www.1000bulbs.com/Screw-In-Compact-Fluorescents/

Tomato Velvet Red seeds are available here.

To give an idea about the value (or lack thereof) of lumens. I just got a 3.8W Cree 60-LED 6500K that delivers a whopping 300 lumens. But, at an inch about the plant, I get a lux reading of 120,000.

The light prism effect (holding a CD at an angle and viewing the light spectrum) shows most bands are covered. Not a continuous one but one akin to a rainbow.

It would be interesting to see how a 8-LED array (2x4) would do, what kind of area it would cover and still deliver 30,000 lux.

Maybe something to while away the hours this winter!

Mike

Ah I see now. (I'm assuming the 120k reading is by putting the light meter an inch from the light, where the leaves would normally be.)

On another note, my tomato plant has apparently been playing me for a fool. Acouple days ago I added some more water to my DWC bucket and the roots were the same as before (Looked like semi-transparent strings all bunched together). I then started leaving the rig running 24/7 (was on 16 on, 8 off), the roots started to create additional roots off the main ones.

Then about 48 hours ago, I finally added some additional illumination to the rig in the form of two white LED arrays. The plant has suddenly gone from barely alive to growing properly! It has started to gain height and the leaves now seem to be growing towards the light!

I'll snap off acouple pictures to show you guys later.

DWC should run all the time. Like you, I have found that the best way to grow plants is to mimic sunlight. My goal is to do it as cheaply as possible! White LEDs may be the best ones yet, especially when used as supplemental light.

A side note - I have noticed that most nuits designed for hypo have a significant amount of nitrogen or one of its derivatives. Maters don't need this - it causes the plant to grow taller which means the grower needs a higher intensity of light to penetrate the plant. And from growing them since I was a kid, a significant amount of nitrogen doesn't do anything for creating more blossoms or bigger fruit. So why increase plant height?

And yeah, the meter was about an inch from the light, at the same distance from the heart of the plant.

My goal is to raise some maters upstairs this winter and harvest 2.5 pounds of fruit per plant a week once they get mature, using the least amount of electricity as possible. The idea between now and then is to find the best way of doing this.

Mike

DWC should run all the time. Like you, I have found that the best way to grow plants is to mimic sunlight. My goal is to do it as cheaply as possible! White LEDs may be the best ones yet, especially when used as supplemental light.

A side note - I have noticed that most nuits designed for hypo have a significant amount of nitrogen or one of its derivatives. Maters don't need this - it causes the plant to grow taller which means the grower needs a higher intensity of light to penetrate the plant. And from growing them since I was a kid, a significant amount of nitrogen doesn't do anything for creating more blossoms or bigger fruit. So why increase plant height?

And yeah, the meter was about an inch from the light, at the same distance from the heart of the plant.

My goal is to raise some maters upstairs this winter and harvest 2.5 pounds of fruit per plant a week once they get mature, using the least amount of electricity as possible. The idea between now and then is to find the best way of doing this.

Mike

Ok, I finally found a Lux meter.

When at the same position as the plant, the meter reads 15000 lux.

Also, I realise I made a mistake in my last post mike, I keep the DWC running continously. The 'rig' purely refers to the leds.

The plant itself has started looking alittle miserable on last check, but I'm just wondering if that's just me looking at it wrong.

Cheers.

To give an idea about the value (or lack thereof) of lumens. I just got a 3.8W Cree 60-LED 6500K that delivers a whopping 300 lumens. But, at an inch about the plant, I get a lux reading of 120,000.

Actually that's the most valuable 300 lumens I've ever heard of. LOL!

taz,

I got it from dealsextreme.com. It was about $12, but if I buy six or so, they are only $10.50 each and shipping is free. I'm thinking about building an array of them, spacing them at first six inches apart and seeing how seedlings grow. Over the next few months, I should be able to try several different distances since it should only take about six weeks to grow a mature seedling. Gotta play with the nuits and find a way to avoid most nitrates. I was at a store the other day and found Better Boy tomatoes that were only three inches tall but had six-eight sets of leaves. I'm presuming the grower used a growth regulator on them - even in natural sunlight they do not grow that compact.

Mike

I've heard to shut growth down completely like flipping a switch by using far red as the last light on at bed time. I've never tried it but will next year. Might be a good test for struw since he's already got a setup like it. He would just have to plug his incandescents in to another timer. How bout it struw?

taz,

I heard the opposite, that removing any far red light at the end of a day does a better job of reducing elongation. Here's an interesting article.

Why wait until next year?! I play the year around, sometimes for a few weeks, other times for 3 months or so.

One thing I found is that a tomato plant with a very unusual name - ITC 06 313, produces fruit that is 6-8 ounces in size, has few seeds, a real tomato taste and very little white flesh inside it. I found it out too late to grow it this summer (it is an Indeterminate so too big for upstairs) but I will try it again in the GH this fall and next year in the garden.

I figure that I might as well be the blind squirrel and keep stumbling along. Sooner or later, I'll find that walnut!

Mike

LOL! Yeah you'll find that nut one of these days. I'm living on a very small budget so when the AC comes on the lights are going off this year. Maybe in the fall? It's hell living on disability especially since we didn't get a COLA this year and probably won't next year either.
My memory isn't what it used to be and I could have got the red and far red mixed up. I'll have to look the article up again.
I might run a couple of T5s over summer but the big boys will be shut down. I'm thinking of pushing 10 14w T5s with a couple 4X32w and one 2x32w ballast to see just what kind of light I can get from them. I just stripped two single T5 fixtures and am in the process of mounting and wiring them to the 2X32w ballast. If it works well I might get rid of all my OD T12s and just run the T5s. If my figures are right they should fall somewhere between HOs and VHOs. I will still be propagating a few plants from cuttings and would rather do that inside to keep them safe from the outdoor elements. I may go with LEDs eventually but for now this setup is more cost efficient since they are all paid for.

Taz,

I understand. I have been really constrained in what I can try because of money. Self-employed, publish a weekly newspaper. Been doing it since '96. The past three months have been - shall we say - a real challenge. Especially since people do not feel they need to pay me. That's one reason I really want to get into growing stuff - I'll get COD. The down side, and this is why I didn't get into it 30 years ago - I have to rely on something I cannot control - the weather.

Hate to digress, but my first year in college, dad gave me an acre of tobacco to grow. OK, it was part of only about 15 acres we grew as a family, but I got the money from it. But... that was the year when 3/4 of the area suffered flood damage even though we got next to no rain. My plot of ground was next to the Ohio river and way upstream, in Pittsburgh and other communities, they had one of those 100 year downpours. The water came down the river. I had two other very small plots - they got hit by hail - one of only two places in the county to report hail damage. It was like a sign, a 1000x500 foot billboard sign that said, Mike, give it up!

Wrong way to read it. A couple of years later, after I had graduated from college and was just helping dad, he lost almost his entire crop to hail. He had insurance (I did too, but because the crop was young I got next to nothing for it, and I think dad kept the payment to cover the cost of the insurance!) and got 100 percent payment. That year, we contracted out our services, especially housing and stripping the tobacco. I think he netted twice what he would have without the hail damage!

Changing topics in the middle of a thread, I did an analysis last evening on what it would cost to raise an additional 500 seedlings next year, based on lighting. The candidates were 23-watt CFL bulbs, 105-watt CFL bulbs, 400-watt MH systems and building another greenhouse.

The analysis did not include operating costs, only the cost to buy/build the system, based on cost per flat (18 plants). What do you think won?

Mike

He would just have to plug his incandescents in to another timer. How bout it struw?

Not on my present test plants. After my present experiment is over, I will move my growth chamber to my basement and start some more Tomato Velvet Red (which I found to be most sensitive) seeds, at which time, I might try it.

Mike, I think the 23w CFL bulbs won, and the 105w CFLs got second...will you share your findings please?

Wood,

You win.

23 watt CFL: four bulbs will cover three flats and cost $10. ($3.33 per flat)
105 watt CFL: one bulb will cover five flats and costs $25. ($5.00 per flat)
Greenhouse: It would cost ~$400 to build one that would hold 57 flats and have room to water them. $7.00 per flat.
Metal Halide: A 400-watt system would cover 10 flats but would cost at least $135 bare-bones. That's $13.50 per flat.

A flat is defined as a nursery tray that is close to 10"x20" and can hold from 18-72 cells. I tend to go with the 3" cells, which is 18 plants.

Over a 10-year period, counting electricity, bulb replacement, etc., the GH would be the winner. But for people who are reluctant to buy green bananas, the 23-watt CFLs win!

Mike

Hey Mike, I just saw some LED's online and wondered something.

The LED's put out 250 mcd over 120 degrees, which is roughly 0.785 lumens.

But does that mean its 0.78 lumen when the LED is directly placed on the light meter or is that 0.78 a short distance away?

This is a problem as there is no one standard that applies to lumens. Usually, manufacturers measure lumens a foot from the source but all that counts, and with LEDs, it doesn't count as much, is Lux. That's the measure of the light's intensity at the plant canopy or wherever you measure it from. It's how my little 3.8 watt, 300 lumen LED light can ring up 120,000 lux 1/2" away.

Mike

I'm curious guys.

I've opened the cover of my DWC rig roughly every week, looking at the root growth then closing it up.

I've recently noticed a brown sludge forming on the sides of the DWC bucket, since there is practically zero light penetration into the tank, I'm wondering if this is a function of what little light enters the bucket or just a byproduct of the water nutrients I've added to it.

In other news, I'm going to add another 2 cool white and 2 warm white LED bulbs, which are considered to be 50w replacements for some other kind of bulb.

I was wondering though, if I should place 2 warm 2 cool 50w bulbs directly above the plant and the 2 warm 2 cool 35w (comparable replacement value) g4 capsules half-way up the plant to ensure the plants get an overall light coverage.

farleshadow......brown sludge could be dead microbes, are you using organic nutrients?

I'm using 'Vitalink GROW', which apparently contains everything a plant needs for vegative growth, when grown hydroponically, I dunno if that is organic or not.

Although the mysterious brown sludge has disappeared from the sides of the dwc, so I'm guessing that it was the nutes after all, especially since the plants are growing at a remarkable rate.

I'll post some pictures abit later.

Well peeps, I know you've been dying to hear about my exploits.

My most recent light rig, with specifications forthcoming, has managed to make a broad bean produce some white flowers.

I will post pictures soon, along with some info about it.

When you are growing with hps, you get a set of day/night differences.
1. 10-15 degrees difference in ambient temperatures.
2. No radiant heat hitting plants at night.
3. Relative humidity will change at night due to lower ambient temps.

You get these three differences just by turning the hps OFF for the dark period.

When growing with LED only, you do not benefit, as much, from these differences, because LEDs emit no heat.

It is these differences people have been overlooking...now we need to add heat, or another factor, to replace the lost differentials, when switching from hps to led....

This is why you see more apparent growth, as you ad more watts of LED; you are adding more heat to your day period, thus creating these differentials.