LIGHTS - how close is too close
 

I'm using LED lights. They're pretty powerful compared to my old grow CFL's. For the 1st week to 10 days, I literally got dizzy/nauseous when I got close to the lights. I turned off the lights before heading into the boiler room

I think it's not due to to the brightness but *brain confusion*, as the LED lights gives off a array of colors, blue, red, white, ir, uv etc.

Anyhow, for the most part, I've had my LED's about 12 inches or so away from the tops of the seedlings. I've tinkered with the dimmer settings (it has 3 modes, seedling, veg and bloom). Since it's sprouted, I've had the seedling on 100% and Veg as well on 50%. Sometimes I'll crank it up more, just to vary the light output. Manuf. recommend height during vegetative state is 24-30 inches. . That seemed awefully far away --- well compared to the mere inches CFL setup....Granted, there is no universal rule when it comes to gardening, and or height/relative to light output/relative to plant response.

Anyhow, what's the rule of lights / seedlings. Just crank them as high as long as it doesn't burn ?

I've got the same lights on my seeded annuals and I have them on FULL blast and they are loving it.

Not sure what the rule of thumb is with 'matoe.

Just crank em as high as long as it doesn't burn.

Try a few inches and watch closely.
I actually got sun scald on a few leaves last year as the plants were touching the lights, I use Fluor and Led bulbs.

[IMG]https://c1.staticflickr.com/3/2875/32876083964_de459d3d8b_z.jpg[/IMG]

You can buy all the lamps you can lay your hands on, they will be less powerful than a bright sunlight. The only limits are the emitted heat reaching the seedlings and your financial means...

Very interesting. So the only thing that can ~hurt~ them is just burn.

Literally, the LEDS make me dizzy/nauseous for the initial 10 days. It needed a ~acclimation~ period for my eyes/sensory brain to adjust.

I just was not sure aside from heat - literally, can too much light or too intense light be a bad thing

You'd be hard pressed to get too much or too intense light from anything that is not the sun.

Nan

Thx all. Anybody else on this forum running similar high powered LED plant lights that is being discussed. Doing a quick cut n paste on the manuf. on how many LEDS :

2pc 100w COB + 140pcs 5w single chips and C850 is 6pcs 100w COB + 100pcs 5w single chips

[QUOTE=ginger2778;691850]Just crank em as high as long as it doesn't burn.[/QUOTE]

I second this. Just keep an eye on them. Don't crank it up and go away for the weekend. Do it when you can check in on them every 12 hours.

LOL. The wife is at home. I have these on a timer plug.

I'm sure my CFL's were made overseas but it's a much simpler light.
These LED lamps have heatsinks, fans, etc.
I turn them off when we are away from the house for more than 45 minutes. Anything just short of a errand run, the lights are turned off. Too scared they will burn my house down ;-0

On the lowest sets of leaves, they are wilting. Only the lowest leaves. I did transplant them from seedling to packs.

Should I lower the intensity or let the lower sets of leaves wilt of thrive ? I don't want to dial back the lights and then have them stretching for light.

MD, if they were transplanted within the past couple of days, it could be just transplant shock. I'm not sure why dialing back the lights would help.

Nan

I don't know if I'm ~stressing~ out the small leaves. Not burning, but stressing them out....


Hard to explain, other than the 1st 2-3 sentences of the original post. Not that plants have eyes or brain. But the LED driven lamps are just very different compared to good 'old CFL. Even now , not that my eyes have gotten accustomed to the color sensation my brain gets----I actually dial down the lights so only primarily the white/blues are on so it won't make me feel a tinge nauseous.

[QUOTE=mobiledynamics;691979]On the lowest sets of leaves, they are wilting. Only the lowest leaves. I did transplant them from seedling to packs.

Should I lower the intensity or let the lower sets of leaves wilt of thrive ? I don't want to dial back the lights and then have them stretching for light.[/QUOTE]

Normal for a new transplant. In 3 or 4 days they won't be wilted anymore. Too intense light would be damaging the top leaves closest to the light. Be patient.

White and blue range are the best light for tomatoes anyways.

Thx ginger. I have no idea how to read the chart but this is the spec on light intensity/specturm[IMG]https://images-na.ssl-images-amazon.com/images/I/61d6uAnNWYL._SL1000_.jpg[/IMG]

[QUOTE=mobiledynamics;692000]Thx ginger. I have no idea how to read the chart but this is the spec on light intensity/specturm[IMG]https://images-na.ssl-images-amazon.com/images/I/61d6uAnNWYL._SL1000_.jpg[/IMG][/QUOTE]

This is telling you the blue range is what's used most for all 3 stages. Also telling you that the closer the light is, the more intense the light is. No brainer there, lol!

Too many dials knobs calculations and adjustments for something that should be simple.
All in the name of robbing folks of their money.
I dont mean to sound rude but I have seen it time and time again.
Worth

[QUOTE=Worth1;692087]Too many dials knobs calculations and adjustments for something that should be simple.
All in the name of robbing folks of their money.
I dont mean to sound rude but I have seen it time and time again.
Worth[/QUOTE]

Bloom time, veg time.... tells me the light is geared towards "Marry Juh Wannah" growers, but for simple seed starting I agree, its just too much unneeded information when all you need is a Kelvin rating, to me that's what I look for in providing lights to my plants, the closer I get to 6000k the better.

Never had a problem.

[IMG]https://c1.staticflickr.com/3/2886/33677915526_7c0d9c3ed7_c.jpg[/IMG]

MD, sent you a PM regarding LED's. Have used them here with greater success than fluorescent tubes. Made by Austin company. They were kind enough to bring umol meter and adjust to optimum/proper light intensity. Started seeds Jan. 1. Plants now in raised beds with blossoms and tiny tomatoes.

Harry - can you send me the company info? I'm curious to take a look. I built my own LED's so I'm curious to see how they compare.

TexTom0, Here is one of their pages: [url]https://fluence.science/technology/ray/[/url]. They really know their stuff. The units are just fantastic, once properly adjusted...expensive, but outlast fluorescent fixtures and tubes. Nope, not an employee, just a happy customer.

Those are nice but expensive. You can buy kits much cheaper online if you're somewhat handy. I built my own COB LEDs, and have some of the Quantum Boards on order now because I like their low profile. They're about $2/watt and are just a board that you hook to a driver.

It is nice how they come help you set up and test the lights. Seems like they're getting ahead of the curve for a new type of home growing indoors.

Regarding getting nauseous from LEDs, it could be from nearly imperceptible flickering. If the power supply doesn’t have properly sized filter capacitors or they used bad electrolytic capacitors that have gone bad, it will cause them to flicker at 120hz (or 100hz if you are in europe). Especially with higher power consumption this might happen. Not to get too far into the details but LEDs take DC power, and your outlets supply AC. The power supply rectifies the AC power into DC and the filter capacitor smooths out the peaks and troughs from the AC voltage into a flat constant DC voltage. If the cap isnt big enough the LEDs will use up the power stored in the cap and begin to dim as the voltage drops. As soon as the next peak in voltage happens, it will charge up the cap and go to full brightness before beginning to dim again. This happens 120 times per second for a full wave rectified DC power supply in north america. Too fast to perceive, but slow enough that it can cause nausea/motion sickness.

You can see it more easily with cheap LED christmas lights which dont usually have a filter capacitor at all and are often only half wave rectified so it happens at 60hz which most people can see.


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NB. No flicker. I think in the literal sense, it was brain shock - and the brain/sensory senses. For the 1st 10 days, I literally turned off the lights before I entered the room as I would get dizzy if not semi-nauseous.

It's now at lease more comfortable - meaning, I can walk in, and head straight to the dimmers, turn off the veg setting (more brightness and red), and the color output is a mix of primarily blue/white with minute red, but because the intensity is less and my *brain* had adjusted, I don't set such sensory reactions.

Very weird non the least....but definitely something new for me as far as running LEDS and the reaction of

I think "weird" is the right word. You could make a test with a common LED lamp in one room of your home (don't buy it, borrow it from a neignbor / friend. just in case) to see if you react in the same way. It's well-known some people can't bear waves coming from phone relays but your case is really exceptional.

All the best

Hi, folks. I'm not sure if this my first post on this forum, but if not it's been a while. 😉Thought I'd chime in on a few things here and there.

I grow my tomato starts in 72 cell plug trays. I use two 8-bulb 6300K T5HO fixtures to cover 9 trays. They give off a lot of heat, so much that don't need germination mats to get the soil up to 85°. I can even put 4 trays on top of each fixture and get the soil up to around 80°, which allows me to use my mats for other starts.

I used a photographic light meter to see how much light falloff I get as the fixtures are raised. In theory, the light intensity should get four times as bright for every halving of the distance, but in the real world the light intensity stops increasing at distances any closer than about 6".

At 6" distance these fixtures give off the same amount of light as we get here (Upstate NY) in our nursery at midday on an overcast day. In full sun the light intensity is over 2 "stops" brighter, which is more than 4 times as much light energy.

Under my lights the air temps can get over 100°F if they are too close. The lights won't "burn" the leaves, but the air temp is way too high for best growth, and the trays dry out and need constant watering through the day. So I aim for about 8" minimum distance once the seedlings emerge, as it is enough light for adequate growth, but not so close as to cause heat buildup problems.

Sorry if my first post seems a bit wordy, just trying to share what I've discovered.

[QUOTE=mobiledynamics;692959]NB. No flicker. I think in the literal sense, it was brain shock - and the brain/sensory senses. For the 1st 10 days, I literally turned off the lights before I entered the room as I would get dizzy if not semi-nauseous.

It's now at lease more comfortable - meaning, I can walk in, and head straight to the dimmers, turn off the veg setting (more brightness and red), and the color output is a mix of primarily blue/white with minute red, but because the intensity is less and my *brain* had adjusted, I don't set such sensory reactions.

Very weird non the least....but definitely something new for me as far as running LEDS and the reaction of[/QUOTE]

I know what you mean. Yesterday I went to the local hydro store to get some fertilizer. They are mostly cannabis oriented, but they have an expensive LED setup with peppers (legal to grow here in NY) growing hydroponically under the light. These things got huge since the last time I was there, but they look so weird under that light that it's a bit disconcerting. I didn't get ill looking at them, but it was not exactly pleasant. Wish I had one, though, they work great.

Hi Lou -

Don't have common led strips vis-a-vis for growing, be we do have LED bulbs in the garage and kitchen (PAR style) which is fine. Way OT, but call me old skool. For lights in the house, I still prefer old school halogens/incandescent. Yes, LED bulbs come in High CRI and similar color ranges of 3K-2700K, but there is definitely a pop or 2 missing from even the most highest end CRI led bulbs versus old school halogens IMO -- I did the conversion in the kitchen due to heat output from the halogens, and that has been a tremendous difference .

It depends on the light technology. Too much incandescent or HPS can cook your plants. Fluorescent can be as close as possible short of touching. LED's are presumed safe but I don't have personal experience using them as I am genetically too much of a cheapskate.


Basically, plants need light like they need water. Either too much or too little will harm or kill them. The term DLI (daily light integral) is the best method of calculating optimum amounts of light for plants.

Attached is a Word doc, spreadsheet and PowerPoint that explains as much of this as you can bear :)

Just want to say how much I appreciate everybody's discussion about lights this spring. I think I was lucky I didn't have the moolah to make a major LED purchase this winter, and couldn't find suitable LED bulbs either for my T8 fixtures, so had to stick with some fluorescents and the couple new LED's.

For all that's been touted I'm not convinced that LED is a really mature technology and not so easy to just swap out your shoplights for the new thing. So I will tread carefully in planning for the future and hold off for awhile on more LED lights, until I'm sure I'm not still in the dark. :?

I interpreted from you post you were running LEDS. All in all - i find it's interesting to observe. With the former lights , at this stage of growth, I would say the stem might be 3+ inches higher than where my current ones are right now The leaves just keep on getting bigger and bushier with not much elongation