# Seedlings burnt by LED?



## sureshot006 (Sep 8, 2010)

Started some pepper seedlings a couple weeks ago. Heat mat set to 80F. I didn't turn the light on until a few days after germination. The 2 lights are 2 ft 24 watt LED and I had them pretty close, about 4" from the plants.

I left the cover on the tray for a week to help the rest of the seeds stay warm and germinate like I normally would. The larger seedlings were starting to touch the cover so I took it off.

2 days after taking the cover off, I noticed what looked like burn on the plants. I then moved the lights up to approx 12" and put the cover back on but propped it up to keep the plants from touching. They are still growing their first set of true leaves and so far I don't see burn on those.

In the past I had used 40 watt fluorescent shop lights with no issues at all. This is first year with "grow lights".

What do you guys think? Is this really too much light? I can't imagine it would be thermal burn as the lights are not hot at all.

@jr28schalm I know you grow stuff...


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## Waif (Oct 27, 2013)

Sure that's burn?

Here's some Jr. type plant browning topics...

Why are leaf tips brown, burnt, or yellow? | Grow Weed Easy


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## jr28schalm (Mar 16, 2006)

Can you feel heat off the leds with back of your hand 4 inches away?


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## John Hine (Mar 31, 2019)

Looks like nutrient burn, you using hot soil? Miracle grow?


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## sureshot006 (Sep 8, 2010)

jr28schalm said:


> Can you feel heat off the leds with back of your hand 4 inches away?


Nope


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## sureshot006 (Sep 8, 2010)

John Hine said:


> Looks like nutrient burn, you using hot soil? Miracle grow?


Nothing. Water and those expanding pellets.


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## sureshot006 (Sep 8, 2010)

Waif said:


> Sure that's burn?
> 
> Here's some Jr. type plant browning topics...
> 
> Why are leaf tips brown, burnt, or yellow? | Grow Weed Easy


Not really sure... I thought it COULD be fungus because of humidity. But it didn't happen at all until I removed the cover.

My only thought with the light is maybe too much too fast after the seedlings had already been up for a few days with no light at all (like you might see from setting young plants in full sun the first day outside.


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## sureshot006 (Sep 8, 2010)

The ONLY difference between this year and 2012-2021 is the lights.

Maybe I should plant a few more of the peppers I really want even if it's kinda late in case these don't make it for whatever reason.


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## Scout 2 (Dec 31, 2004)

What is the brightness of your light I think is Lumens. I cannot imagine it is the light as they have grow lights that are on a dimmer


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## PunyTrout (Mar 23, 2007)

On a somewhat related note, I transplanted a few of my Reaper/Naga jolokia hybrids into pots last fall and have kept them alive all winter. They're doing great and some are trying to flower. If the transplanting outside is successful there should be enough peppers to feed/poison anyone on Michigan-Sportsman interested in trying them out later this year. 

I did a similar thing with a Thai bird's eye plant a few years ago and they turned into trees with hundreds of peppers that I still have dried in jars when needed.


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## sureshot006 (Sep 8, 2010)

Scout 2 said:


> What is the brightness of your light I think is Lumens. I cannot imagine it is the light as they have grow lights that are on a dimmer


Not sure about lumens but PPFD for each light is ~200 umol/m^2 s at 8"


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## DirtyCuffs (Sep 22, 2016)

Are you top watering or letting it wick?

They look like they should be fine. But I would put the lights back closer or they may start to reach and get lengthy. As long as your hand doesn't feel hot then that's as close as it can go. I have been using fluorescents for decades and my seedlings are always up in them touching the bulbs. I only raise when they start to bend. I have never switched to led so I don't know if they feel hot. If you want the humidity then get rid of the cover and drape clear plastic over the light and all and mist daily


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## jr28schalm (Mar 16, 2006)

sureshot006 said:


> Nope


When I've used led I try to keep the light a foot above to 18 inches..


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## sureshot006 (Sep 8, 2010)

jr28schalm said:


> When I've used led I try to keep the light a foot above to 18 inches..


I figured these were weak enough to be okay but maybe not... I was hoping to stay in the realm of 400 ppfd.

Does it look like too much light to you? Or something else?


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## Ieatshrooms (Sep 19, 2019)

sureshot006 said:


> I figured these were weak enough to be okay but maybe not... I was hoping to stay in the realm of 400 ppfd.
> 
> Does it look like too much light to you? Or something else?


I've seen the results of plants too close to lights, and it doesn't look like that is the case here. The light damage is a more distinct bleaching, and not so much of a yellowing around the edges of the leaves. Your plants look more like a nutrient/water issue, but also not really alarming.


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## DirtyCuffs (Sep 22, 2016)

Ieatshrooms said:


> I've seen the results of plants too close to lights, and it doesn't look like that is the case here. The light damage is a more distinct bleaching, and not so much of a yellowing around the edges of the leaves. Your plants look more like a nutrient/water issue, but also not really alarming.


exactly. My guess is watering.


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## DirtyCuffs (Sep 22, 2016)

This is not an issue of too much light. You are only pushing 2 24 watt leds


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## sureshot006 (Sep 8, 2010)

Ieatshrooms said:


> I've seen the results of plants too close to lights, and it doesn't look like that is the case here. The light damage is a more distinct bleaching, and not so much of a yellowing around the edges of the leaves. Your plants look more like a nutrient/water issue, but also not really alarming.


It certainly could be water (too much). When I had the cover on it didn't dry even at the surface for 2 weeks. I could have had excess water sitting in the tray and didn't know it.

I've never used any additional nutrients for starting seedlings until they get the 2nd or 3rd set of leaves, then I just put them in miracle grow potting mix. Haven't seen anything like this. I'm curious what the first set of leaves will do. So far they look good.


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## sureshot006 (Sep 8, 2010)

DirtyCuffs said:


> This is not an issue of too much light. You are only pushing 2 24 watt leds


Yeah I was thinking if anything it was not enough but the appearance was making me think twice.

I'm gonna let then dry out a little bit and see what happens. Maybe it was too much water.


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## DirtyCuffs (Sep 22, 2016)

Try just letting them wick water from the tray and not top water them. I do not topwater after sprouting has occurred. I just keep enough water in the tray to reach about a half-inch to an inch above the bottoms of my cell cubes. This will ensure that your plants will have a constant regular moisture level while also allowing you to avoid overwatering and mold or root rot issues. Use plastic sheeting to cover the whole setup to hold humidity. I have been growing since the 90s and this has always been how I do it


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## sureshot006 (Sep 8, 2010)

Waif said:


> I'm late to be starting tobacco seedlings...
> Seed starting mix is different than potting soil.
> I passed on a bag of it due to being far more than what I need in volume. but should have grabbed it.
> 
> ...


Yeah I'd never use potting soil for this. Mix is good though, AFTER the roots are established.


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