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lighting LED lights - again

W

wordwiz

I've had a hydro system set up for a few weeks, running under a 112, 10mm bulb system that was orinally about three feet from the plant canopy. The peppers have been doing great, the toms were getting quite leggy. For better or worse, I topped the toms and left them about three inches tall. (The tops went into a cloning solution - hopefully they will survive) They will live or die, as plants are wont to do.

But the reason for the exercise was to get the light closer to the plants and see how they react. The light hangs about a foot above the plants' canopy and is delivering about 6,000 lumens of nothing but red and blue light.

This week, the project is to sow a couple of toms and a couple of peppers and once they sprout see how they do under the light. My early observation are the peppers love the red/blue mix, the eggs adore and go ballistic under them and the toms like lights that have more blue.

Mike
 
Very keen to see your results.

I did quite a bit of reading about LED recently, to see whether it was a viable replacement for the energy succking 600W HID lamps I'm running. Right now, I think its a new technology that will eventually work great, but just doesnt seem to be spot on. The initial investment costs for decent high powered LED's is significantly more than HID as well.

You might find that although the plants grow and flower well, there might be a lack of fruit. Some of the websites I have been glancing over show a significent difference in fruiting with different lamps, with no other conditions altered. Be very interested to see how your one goes.

Is it a name brand by any chance?
 
wordwiz said:
The light hangs about a foot above the plants' canopy and is delivering about 6,000 lumens of nothing but red and blue light.
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How did you arrive at the number of lumens that your lights put out?
 
The initial investment costs for decent high powered LED's is significantly more than HID as well.
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I don't see the investment being much higher. A 600 watt HID system is what - $275 give or take. I don't know exactly how much area the bulb would cover. I would need four of the LEDs to cover 288 seedlings and the cost would be about the same (~ $260). But the savings in electricity would amount to $20/mo.

You might find that although the plants grow and flower well, there might be a lack of fruit.
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That is one of my fears with the hydro system. Obviously, for seedlings if won't make any difference. Hopefully, I can let you know in about 60 days!

How did you arrive at the number of lumens that your lights put out?
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A LUX meter. It was taken at night with no ambient light present.

and red/blue alone has proved only good for vegetative growth.
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Not completely true. Josh at http://www.greenpinelane.com/ has done some tests. I really like his systems but I don't think I could afford (or know how make) the ones he has used.

I guess this is what I will find out. If blooms set but not fruit, I can can add some 2700K CFL lights to the sides.

My goals are not that high, at least not yet. I want to be able to have fresh tomatoes and lettuce (and possibly cucumbers to eat this winter without having to buy them from the store, plus raise seedlings. Josh's test showed tomatoes will produce nicely, though he didn't have as much success with peppers (he wrote that he was not growing them under optimal conditions, however).

Mike
 
willard3 said:
NatGM:

Most lamp purveyors will tell you the lumens for the lamp. Google "250w metal halide lamp"
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Thanks Willard, I've been using lights indoors for more than 25 years. I was trying to understand what *your* level of learning is...;)

Lux and lumens are pretty close to the same. The formula for conversion is one complicated SOB, but for small scale plant growth, lux is close enough.

Did you measure at canopy level?

What's the optimum lumens per/sq.ft at canopy level for peppers? 6K seems pretty low for an over-all lumen output.

Natural sunlight is about 10K lumens per/sq.ft on a clear day in the Southern USA in summer.

For most of my inside grows, I shoot for 5K per/sq.ft at canopy level which gives me excellent growth on all the veggies I've grown indoors. I use only Hortilux, LU 430S/HTL/EN bulbs with bat-wing reflectors at 18 inches from the canopy.

These lights give about 80% of the usable yellow and about 50% of usable blue as compared to the plant sensitivity curve. My best was with Maters. The cherry maters grew so fast it was stupid.

As you know, the lumens rating for lighting is an industry standard of the light at exactly one foot from a globe. The ratio of light as the distance increases radically decreases the amount of lumens at canopy level.

With LED's, you should be able to use them at just a few inches from your plants, if that gives you enough spread.
 
I grow at 4k lumen/square ft at plant canopy. I also have a skylight the whole area of the greenhouse so I don't do it all with electricity.
 
I measured the light at the plant canopy.

Granted, 5K doesn't sound like much, but my 4-foot fluoros were only putting out 1100 lumens at the plant canopy. Two 23 watt (100 watt equivalwent) CFL bulbs produced about 3400 lumens at the canopy. In theory at least, I should be able to move the lights up about six inches and still have more light than the CFL lights were producing and double what the regular fluoros produced, and I had a couple of pods develop on the peppers.

I have another system set up that holds three plants, a tom, Habanero and Eggplant. The egg is going nutsy cuckoo under it, perhaps because I'm using 30-10-10 nuits. I'll have pics later this evening. This is also a red/blue light but uses only 13 watts instead of 45 and has 226 3mm bulbs rather than 112 10mm ones. I can grow about 324 seedlings under four of these. Not bad for 52 watts of energy.

I have found that I need to mist peppers daily (at least once, twice is better under a light that is tuned more to the blue spectrum. However, I was not impressed with plant growth - it was bushy but didn't get very tall.

Mike
 
I think sometimes that the total of the blue and red parts of the spectrum's lumens/lux may be lower with HID lights.
All the other wavelengths may actually be stressing the plants. Putting up barriers and pumping more water to leaves to protect itself.
The blue and red lights are intense enough that it has all it's needs met. My purple tiger decided it didn't need much green cells in the leaves anymore, but of course, it's using the stem's chloroplasts to make sugar too.
681k​
 
willard3 said:
I grow at 4k lumen/square ft at plant canopy. I also have a skylight the whole area of the greenhouse so I don't do it all with electricity.
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I wish I had some skylights. As soon as my next batch of seedlings are ready, into the ebb and flow they go with one 430W at first and two after they get large enough to use them.

What peppers have you grown inside? This is my first time with peppers.
 
wordwiz said:
I measured the light at the plant canopy.

Granted, 5K doesn't sound like much, but my 4-foot fluoros were only putting out 1100 lumens at the plant canopy. Two 23 watt (100 watt equivalwent) CFL bulbs produced about 3400 lumens at the canopy. In theory at least, I should be able to move the lights up about six inches and still have more light than the CFL lights were producing and double what the regular fluoros produced, and I had a couple of pods develop on the peppers.

I have another system set up that holds three plants, a tom, Habanero and Eggplant. The egg is going nutsy cuckoo under it, perhaps because I'm using 30-10-10 nuits. I'll have pics later this evening. This is also a red/blue light but uses only 13 watts instead of 45 and has 226 3mm bulbs rather than 112 10mm ones. I can grow about 324 seedlings under four of these. Not bad for 52 watts of energy.

I have found that I need to mist peppers daily (at least once, twice is better under a light that is tuned more to the blue spectrum. However, I was not impressed with plant growth - it was bushy but didn't get very tall.

Mike
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Keeping the intranodal length compact is difficult under low light conditions. However, I have seen some pretty cool grows under the level of light you're using.

It won't compare to a 4 or 5K per/sq.ft lighting though. I can't wait to get some peppers going.
 
Nat,

The intranodal growth in the peppers is very small using either the light geared more toward red or the bluer light. The tomatoes have been a different story, though if I get the light real close I seem to be able to cut it in half. That's one reason I had to top my plants (and hope they survive). They were going to be six feet tall before any blooms set.

Here's my pepper under the weaker light:
After being transplanted to hydro last Saturday

pepperwk1.jpg


And today (I edited the image to make the distance between the leaves a litter easier to see).

pepperwk2.jpg


My tomato after being put in the water:

redtomwk1.jpg


And the plant today

redtomweek2.jpg



Mike
 
Hey Nute, it sounds as if you have a keen interest in the subject.

There may be a lot more studies than you're aware of. Try a "Google" on "Plant Light Studies" and you'll get about a million results, literally.

The subject has been studied in depth for many decades. Plant reactions to light during growth phases has been the subject of many studies and books. The book I mention below is a study concerning mostly natural light, but can easily be related to artificial lighting by nm and intensity. Plant physiology and biochemistry studies that are restricted specifically to artificial lighting with emphasis on LED technology are intensifying within the last decade and shows a marked increase as a study of choice in many Universities worldwide. It's really quite exciting. I share your enthusiasm for the subject.



Here's a good one:

Light and Plant Responses: A Study of Plant Photophysiology and the Natural Environment

The author discusses the ways in which higher plants respond to natural light environments throughout their life cycles. While previous texts on the subject have used the various light responses simply as a means of illustrating the molecular interaction between photoreceptors and cell metabolism, in this book the ways in which the plant detects, interprets and responds to the natural light environment are fully discussed. It takes a holistic rather than a mechanistic approach concerning the influence of natural light environments on plant growth and development, as well as discussing the recent research in the rapidly developing field. The emphasis is placed on the ecological implications of studies in plant physiology and biochemistry.
 
wordwiz said:
The intranodal growth in the peppers is very small using either the light geared more toward red or the bluer light. The tomatoes have been a different story, though if I get the light real close I seem to be able to cut it in half. That's one reason I had to top my plants (and hope they survive). They were going to be six feet tall before any blooms set.
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That's a fine looking pepper and tomato plant. I don't think you'll have much luck growing them both at the same time under the same light. The tomato growth will dwarf the pepper. You might try using a *lot* of LST on the mater. Wrap that puppy around the pot a few times while the pepper grows.;):lol:

I'll enjoy watching your process.

Good luck to you!
 
NatGreenMeds said:
Keeping the intranodal length compact is difficult under low light conditions. However, I have seen some pretty cool grows under the level of light you're using.

It won't compare to a 4 or 5K per/sq.ft lighting though. I can't wait to get some peppers going.
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People who haven't tried the leds shouldn't say they are weak.
I don't have low light conditions. My camera sees so many lumens that it won't provide much flash power, the aperature is restricting light, or the shutter speed is too quick, making my pictures appear much darker that real life. Darn automatic cameras. It's brighter than hell.
The leaves don't need as many chloroplasts to fulfill their function. The purple tiger or other varigated peppers have low sugar needs.
The internodal lengths are very short. The stems are still weak because they grow so fast and stress free, they don't need to toughen up, form heat resistance, or insulate against the harsher full spectrum light. My plants are wimps because they don't have enough wind. I have a ceiling fan on 24/7 that is keeping the plants in motion, but I don't think it's enough.

Nute there is no conspiracy. If you want to use more electricity by adding more bulbs, that's fine, but substituting with colors other than the 2 red and 2 blues that are sold as plant light, will not give better results.

I just bought one of the pre-assembled $65.00 cree lights today, because I don't trust my soldering skills.:(
I'm probably going to need sunglasses.:cool:
 
ABM,

A link to the site you bought it from?

I'm not that concerned about the tom vs. egg vs. pepper fight to grow. The system was donated to me so I could display it at the County Fair, part of the theme: A County Fair for an Urban Society. It will be sold via a silent auction. The other system - the couple donated two - has two toms in it. If I need to, I can swap the plants and have the egg and pepper in one system and the toms in the other. That is probably what I should do, except the other light is very blue. Maybe better for the pepper and egg?

Mike
 
ABurningMouth said:
People who haven't tried the leds shouldn't say they are weak.
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We all have our opinions. We're all free to express them. We all may not agree on everything.

No attack was meant.
 
I might have sounded harsher than I meant to. Sorry.
I just wish everyone could see these things in action in person.
Mine are only the 13-16 watt kind, but my plants love em.
 
ABM,

The display at the fair is meant to show how even someone living in a 1-bedroom apartment can grow tomatoes, peppers or whatever they want in a small amount of space. I don't want to mislead people but at the same time, I want to have a nice representation of how hydro works. I suppose someone might have a preferance for a pepper over an eggplant or a tomato over a pepper, but I'm thinking they would really be bidding on the system. But it would probably be a better looking display if the plants in each system were the same size. As of Tuesday, I'll have three weeks before I deliver it to them. The two stands are side-by-side so I can flip the lights daily. BTW, the lights are not part of the systems!

Mike
 
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