LED feed demands

[eyesdownchronic]

Why must I give my plants all these extra additives at the same par value under different colors?

I can understand that they are more efficient and that 50w white led is 100 w blurple; but forget about watts, we talking par now.

Can you, or someone here give me the logical explanation? I hate it when I don't understand something so please enlighten me.

You may see a needed change in formulation because plants behave differently when under different wavelengths of light.

Blue light causes plants to grow smaller, tighter leaves, with thicker cuticles. Blue light also causes plants to create additional anthocynanins with the purpose of dissipating excess light energy. I'm not entirely sure but I also imagine that blue light would promote extra chlorophyll production, which is exactly where increased N and Mg come in.

 

[THC123]

Thank for the explanation.

But this gave rise to a new question: if blue would cause this, then why don't I have this issue under 250 MH or a Blue vegging LED?

I would still be cool if in the future this white led only issue could be solved by spectral adjustment. Cant wait to see what leds will bring in ten years.

 

[SuperBadGrower]

Nichia:

Seoul:

its not only spectrum...some who switch from MH or T5 just have no idea. they buy a LED light and suddenly they are vegging with 500 PPFD instead of 200, then stuff goes wrong and they blame the spectrum. When the real culprits are (or may be) diffusivity and intensity, or low temperatures for example

That's why I dont really like "led deficiency" or something like that. It's just light; light is light. Delivered in different ways. The environmental variables are very entangled in the equation.

No point in getting dogmatic about it anyway, as some people love to, hehe. we all observe different things in different environments with different plants.... the real info bombs are right around the corner, all we have to do is wait a few years for some more published research.
I think there is something to the blue light thing, like eyesdownchronic and I wrote about. Still, just a piece of the whole puzzle

 

[eyesdownchronic]

Yeah, blue light ie spectrum is just one example of the differences between the wavelenths between leds and hids, and even full spectrum vs blurple .

Far red to red ratio is another important wavelenth indicator, and a lot of leds have specific additions of 730 nm red. Far red has a lower absorbtion rate than does red, so it is able to penetrate, (to some extent) through leaves. This means that plants which are in shade (or parts of the plant which are being shaded out) have a lower red to far red ratio. Plants have adapted to perceive this stimulus and react by stretching, (i think the response may be triggered by GA, cant rememeber.)

** personal tirade** I have seen online sources (and light manufactures) say things along the lines of, far red light stimulates plants to grow faster, which is just not true, misinterpraetation of the truth. If by grow faster, you mean increase internodal length than i guess. But generally excessive stretch is an unfavorable response most try to avoid. I guess someone correct me If im missing some info here. (This response is independent of photoperiodism)

Anyways long story short there are a bunch of differences between just blue and red v and full white light. With the two i mentioned being major ones.

 

[eyesdownchronic]

Additionaly, as other people in this thread have mentioned, hids and leds have very different heat outputs. This changes the ratio of photosynthesis to respiration. Temperature also directly affects transpiration thereby water uptake.

 

[slownickel]

Everyone runs out of Ca and P early on. With LED's, uptake is less as there is not as much evaporation. Things build up quick and hit the walll quick.

Need to get that Ca and P up early so you can feed gently, not trying to play catch up. Especially on LEDs.

 

[THC123]

Thanks guys, very intersting info.

I see in the optisol spectrum that it has just a bit more blue than the sun. Maybe that's the issue? WHo knows. I still really think the spectrum is still very imperfect though a huge improvement over the past. Remember I have a par meter and I kept the same value when switching from blurple to sf4000. It's not the ppfd, although, like you explained earlier quantity is not quality so even though it is the same ppfd, the plant can use a lot more of it and that can also explain it.

To make a long story short, I want a lamp with a white spectrum that actually can grow plants more or less like in the sun. We aren't there yet. They should try to match it 100%. Even if certain wavelenghts are not needed according to research, maybe this messes up the balance a little bit..

I have tilted the 250 watt MH in my motherroom almost vertically to change the spectrum for my vegging plants under the sf4000.

Lets see what happens...I am curious to see f they react the same way as when the viparspectra was there, even though it has much more blue. And I want to repeat the test with the SF4000 + viparspectra after my a5 grow again. I had a feeling that under that combination of light they were much healthier, they were really looking stellar and superhealthy under that combination. Much better than only the vipar or the sf4000 alone.

 

[voidpainter]

I'm seeing some funky stuff running LED. This showed on 3 out of 9 cuts of the same strain in about a week under LED. There's a day difference between pictures.



The same medium mix is used for mother plants under CFL and some cuts growing outdoors = all these plants are healthy green.


Any ideas? I have raised the lights a bit but I'm totally in the dark as to what is happening. PPFD in the pics was around 280, by raising the lights I lowered it to around 200. I'm not sure whether this will help.



This only appeared on older leaves, the new growth as seen in the bottom right corner is nice green.


rH 70%, 24°C, medium pH 6.8

 

[THC123]

Thats what happened to my seedlings in fresh soil( weeks after transplant) My other plant look similar but no brown spots but the top leaves have the same stripes you have and are paler.
µ
I solved the spots with calmag and extra nutes (way more than I would EVER give a plant under any other lightsource).

Btw also you new growth doesnt like 100% looks pale and exhausted. Same problem as me.

Just read a bit back superbadgrower gave some good info

 

[voidpainter]

Thats what happened to my seedlings in fresh soil( weeks after transplant) My other plant look similar but no brown spots but the top leaves have the same stripes you have and are paler.
µ
I solved the spots with calmag and extra nutes (way more than I would EVER give a plant under any other lightsource).

Btw also you new growth doesnt like 100% looks pale and exhausted. Same problem as me.

Just read a bit back superbadgrower gave some good info

Thanks.

I’ll trial a plant with epsom, I think I have a ton of Calcium in there from calphos, lime, gypsum and crab meal.

I came in here thinking this soil will melt plants but I guess it’s not strong enough for led, lol.

Edit: I found this gem under a different topic, pertains to LED feeding:

Under LED?

Going off what PLC’s website says, If you shoot for a target range of ~75ppm Mg per gallon of water for foliar, then three grams per gallon should do it.

“Common hydroponic fertilizers recipes, usually contain between 40-60ppm Mg. We have found that a range or 75-90ppm of Mg to ideal under LED lighting. The best way to increase only Mg and not introduce more nitrogen, is to add 1gram of epsom salt(Magnesium Sulfate) per gallon of nutrient solution. 1gram/gallon of epsom salt adds ~25ppm of Mg and 30ppm of S, and is usually a sufficient supplement to most fertilizer programs.”

 

[THC123]

I had same problem, I know they needed more calmag, so I added dolomite lime, worm castings, rock dust (all sources or trace elements) But I guess they needed more time to break don as I didn't cook my soil first.

At this point I am not sure even if using only water with a good soil mix will work. Because just like you I added literally MORE then enough in the soil. It is like they can't access what's in the soil for some reason.

But yeah it's a learning curve and things you know about growing don't seem to apply under white ld, everything changes.

From one side it really sucks, as only white leds give these issues. But on the other hand, it is worth the trouble as they consume so little energy for the light and coverage that they give.

But it is annoying having to give so many supplements .

Have you tried dimming your lght yet? I still have to try and dim my sf4000. I am reluctant as the micromoles they are getting now is nothing special(the same as under other lights, about 250-300 only and still these symptoms.

 

[voidpainter]

I “cooked” the soil for about a month. None of the plants under other lightsources show these symptoms.

It’s true that I didn’t ammend heavy with magnesium tho that’s why I’m gonna do trials with epsom.

To me all this sounds like chlorophyl problems more than anything else, but what do I know.

My light is running on 25% power (150W). I started with 15cm hanging distance, this gave me ~280 PPFD. I raised it to 30cm yesterday thinking it might be too much for this stage of plant, which gives me ~200 PPFD.

 

[THC123]

Yes I know thats the frustrating thing, under any other light source (even old leds) perfect plant that give great yields with just the right amount of nutrients. You know the soil, the recipe, the plant, and then all of a sudden nothing works anymore.

I get you lol, been annoyed by these light since January, they have potential but there is something amiss. Sure you can fix this according to many and I am sure because I have seen great pictures under these white leds.

But I just hope that they will also yield much more if you have to give that many more nutrients and additives.

Still like I said, the spectrum needs adjustment so that they behave normally just like any other lightsource imo.

 

[voidpainter]

Since the debate steered towards spectrum, Here’s the spectrum of the light i use:

Im gonna go ballistic with Mag on one plant and will report back here in a week.

 

[THC123]

It seems good for flowering, what led is it?

One thing I forgot to mention, for me what work best is raising the light a lot and dimming less. Did you already try that?

My plants woul totally yellow under the fluence at only 200 ppfd when I used the recommended distance. When I raised to light to about one metre and on max setting They got +-300 ppfd and not bleaching.

 

[voidpainter]

I raised the light 2 days ago to 30cm height from the initial 15cm. I didn’t change the power tho, still at 25%. Apart from those “rust” spots and Mg stripes on some young leaves the plants are growing fantastic.

Im using Lumatek Zeus 600W PRO

 

[THC123]

I would raise the light to about a meter and set it on max or in any case turn the dimmer up.

You will see they will go better. And then gradually lower it and keep an eye on ppfd. I have a fluence which is basically the same. They also say distance to canopy 15 cm. I tried, and also 30. Then I just ignored it and put it higher because it just fried the plants.

It is strange however cuz I have a par meter. ANd200 micromol at 15-30 cm fries them yellowing and all, but 300 micromol at 100 cm lght distance was no problem (concerning the yellowing I still got droopy blue plants under that light).



Mine look fantastic since this morning. Here and there not 100% but wow.

What I did was I topdressed them 2 weeks ago with magnesiumlime. I gave epsom salts an topdressed extra nutrients (double than what I would give normally. But yesterday evening I sprayed them with epsom salts and then 2x 500 mg aspirin c. And now they are looking so much better.

Reason I tried this was that they sell a product called led protect. It is expensive and the main ingredient apart from calmag and micronutrients is salydic acid. Members here said it was the main ingredient in aspirin. And research papers confirm this is a hormone that is produced by the plant in stress situations to cope better.

All I can say is it works. I have a bottle of calmag+ on the way (because it contains them in the right proportions) and I will be adding aspirin to it to make my own cheap led protect.

I still have to use it more often to be certain, but the difference between yesterday and today is dramatic!!

Try it voidpainter! the combo with calmag or epsom salts and some foliar food with micronutrients with the aspirin.

Those micros are also in wormcasting and rock dust etc but they break down way too slow if you want to fix the problem fast. But in theory, how I see it now, for the next soilmix I will be adding a lot more lime and a lot more ingredients with micronutrients and I will try to amp up the bacterial life. Because then they would have everything (except from the acid, but I think healthy plants that have everything they need won't need that).

Still it is confusing because in my actual soil mix there should be more than enough, so really have to guess right now in what way to increase quantity without overdoing it. I also think topdressing every 2 to 4 weeks instead of every 6-8 weeks.

 

[Guest]

Since the debate steered towards spectrum, Here’s the spectrum of the light i use:

View Image

Im gonna go ballistic with Mag on one plant and will report back here in a week.

What did you use to capture the data on your light spectrum ?

 

[voidpainter]

What did you use to capture the data on your light spectrum ?

I didn’t, was provided in the manual by the manufacturer.

@THC123 I dozed them with 1gram/1Litre of epsom yesterday. I also watered a small amount with homemade instant kelp. When I checked on them today the change was fucking stunning! Praying like crazy and the new shoots that were pale-ish with an onset of the classic Mg stripes have started getting darker green. I will just keep dosing them with Mg and/or instant kelp every couple of days. I didnt change the height or nothing. Will do my best to get some before/after pics on here.

 

[Horselover Fat]

I'm on my second run using 3500k lm301b led boards. I'm running at almost 1200ppfd. First grow was small plants in soil. At around 3-4 weeks in the plants got too close to the lights and had they had started to show mg problrms already. This time I have one big plant in hydro and it's just past three weeks. Things are looking good this time. The tops got too close to the lights and showed it, but no mg problems yet. I add about 0.5ec cal/mag as my water is only 0.1ec out the tap. In veg I added nutes to about 1.5 ec and now around 1.8. This is my first time doing hydro. The plant drinks a lot and the EC goes up, but I add water with a little less nutes to bring it back to around 1.8 every couple of days.