How has the transition to COB lights effected your grow style?

It's a long story, here is the shortest version I can come up with: I have four plants, and really for my space I should have three. So the fourth one is going to live its whole life under a cheap LED shop light that I've had great success with up to now just to veg under. All four are in identical soil. The one under the shop light looks absolutely healthy, and the others are showing various kinds of nute +/- stress.

This supports a hypothesis I've had since I first started to work with COBs, that when you intensify the light source, it makes the rest of the variables more critical -- specifically, it makes nute imbalances less forgiving. Anyone else find this to be true? I suppose if you were coming from HPS/MH to COBs, it might be less of a learning curve. I went from CFLs to low power/3w LEDs, to COBs.

I'm also curious if anyone has found that they have healthier grows with COB lights when they do hydro vs. soil?

Humanrob said:

It's a long story, here is the shortest version I can come up with: I have four plants, and really for my space I should have three. So the fourth one is going to live its whole life under a cheap LED shop light that I've had great success with up to now just to veg under. All four are in identical soil. The one under the shop light looks absolutely healthy, and the others are showing various kinds of nute +/- stress.

This supports a hypothesis I've had since I first started to work with COBs, that when you intensify the light source, it makes the rest of the variables more critical -- specifically, it makes nute imbalances less forgiving. Anyone else find this to be true? I suppose if you were coming from HPS/MH to COBs, it might be less of a learning curve. I went from CFLs to low power/3w LEDs, to COBs.

I'm also curious if anyone has found that they have healthier grows with COB lights when they do hydro vs. soil?

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Yes the faster you push the plants the less forgiving everything will be. I was talking just about this same topic to a horticulturist the other day. He said it becomes more difficult as PPF goes up. I tend to agree. Everything is happening faster so if you have something wrong it will manifest that much faster.

Stephenj37826 said:

Yes the faster you push the plants the less forgiving everything will be. I was talking just about this same topic to a horticulturist the other day. He said it becomes more difficult as PPF goes up. I tend to agree. Everything is happening faster so if you have something wrong it will manifest that much faster.

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Thanks for that, its good to know I'm not completely nuts.

With that lowly shop light in my veg space, I've been able to hang it 10-12" over young plants, and get lush green leaves and very short inter-nodal distances. Then I replaced it with a DIY light with 2 Cree 3070 5000k COBs running at about 50w each, and I haven't yet found a sweat spot where it is close enough to encourage short node distances without being so close that it (simply put) hurt the plant.

I understand that more accurately, my FFOF-based soil was hurting the plant, but the more potent lights may have accelerated or exaggerated the damage because when I've used that soil under CFLs or 3w-based burple LEDs, its been fine. Which made me wonder if it were possible to have specific light-type / soil-type combinations that did not work well together?

It appears that I've upped the ante moving to COB lights, and now I have to rethink my grow medium. Currently my 2x4 tent has a DIY light with 8 Cree COBs, and I'm only running 4 of them right now (@50w each), and the plants are totally... challenged.

Yeah. Maybe look into some additional nutes. I'm curious about sanctuary soil

One would think if you can't use soil/nutes that will grow proper under sun then something is fundamentally wrong with that lighting source.

I have not had the pleasure of growing under this new cob tech but know that "regular" grow regimens work fine under both Inda-gro and HPS

OneHitDone said:

One would think if you can't use soil/nutes that will grow proper under sun then something is fundamentally wrong with that lighting source.

I have not had the pleasure of growing under this new cob tech but know that "regular" grow regimens work fine under both Inda-gro and HPS

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I wouldn't think so. To many successful grow journals. It would be good to see his light levels. These cobs will surprise you on how much par your plants are receiving. The surprise thing with some LEDs is you need more ppm or nutrients. The plant is receiving alot of light without the added radiant heat usually involved with other light sources. Basically the plant isn't drinking as fast so nutrient to water ratio needs to be increased to compensate. I can totally see cobs in veg outrunning ffof. I may be totally off on this but pretty sure I'm not.

I am now having great results under my 92watt light compared to the 160w and 196w. Am using super soil mix in all and the 92w put out over 4 oz. the 160w showed more deficiencies and the 196w even more so. I had to add supplements to all but the 92w. I was thinking I had too much light for what was there now I have just purchased 2 more Inventronics quad driver 700mA. I have 5 already but they are on spare lights(3070's) I'm using 3590's now except the 92w is 2-3590's and 2-3070y2's. I was wondering if it was just me.

medicinehuman said:

I am now having great results under my 92watt light compared to the 160w and 196w. Am using super soil mix in all and the 92w put out over 4 oz. the 160w showed more deficiencies and the 196w even more so. I had to add supplements to all but the 92w. I was thinking I had too much light for what was there now I have just purchased 2 more Inventronics quad driver 700mA. I have 5 already but they are on spare lights(3070's) I'm using 3590's now except the 92w is 2-3590's and 2-3070y2's. I was wondering if it was just me.

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That's why I'm a salts man myself. Easily rectified. Maybe look into some water in nutrients to add some extra ummph to compensate.

With the light source lacking infrared and greatly upsetting the way a plant naturally functions with water and nutrient uptake, I can not for the life of me see why anyone who is into "organic" or "natural" or the whole "ROLS" thing would even consider using cob's or led at all for that matter.
If you are looking for things to happen as natural as possible this is clearly not the ticket.
Now if your just the mad scientist type as I tend to be, then maybe these could be for you

Last race car was twin turbo for me lol. So yeah I like to push the envelope. I just try to use synthetic nutrients that are low in heavy metals. They still are salts from the earth. Just readily available.

I'm still at the beginning of the learning curve with diagnosing nutrient deficiencies and excesses. I suppose my less demanding previous lights let me get away with a lot. Recently I was reading @captainmorgan saying that GG#4 needs less nutes than most people think (sorry about paraphrasing), and that's one of my girls, so that combined with the stories of FFOF being too "hot" and burning plants, I was assuming this plant was getting too much of something... but now it seems that people are saying intense lights require more nutes, and it might be somehow under fed?

What do you think?

Humanrob said:

I'm still at the beginning of the learning curve with diagnosing nutrient deficiencies and excesses. I suppose my less demanding previous lights let me get away with a lot. Recently I was reading @captainmorgan saying that GG#4 needs less nutes than most people think (sorry about paraphrasing), and that's one of my girls, so that combined with the stories of FFOF being too "hot" and burning plants, I was assuming this plant was getting too much of something... but now it seems that people are saying intense lights require more nutes, and it might be somehow under fed?

What do you think?

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Need more info. Your using 100% FFOF? Are you feeding too? If so what are you using and how much?Using any additives?

Humanrob said:

I'm still at the beginning of the learning curve with diagnosing nutrient deficiencies and excesses. I suppose my less demanding previous lights let me get away with a lot. Recently I was reading @captainmorgan saying that GG#4 needs less nutes than most people think (sorry about paraphrasing), and that's one of my girls, so that combined with the stories of FFOF being too "hot" and burning plants, I was assuming this plant was getting too much of something... but now it seems that people are saying intense lights require more nutes, and it might be somehow under fed?

What do you think?

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Looks like it needs more base nutrients honestly. Capitan will be better to listen to than me though. I did 1 run organic lol.

Looks a little mag hungry to me. When did you last calibrate your PH pen? I ask this because I had been lazy till last night and mine was off enough to give me some trouble...

PerroVerde said:

Looks a little mag hungry to me. When did you last calibrate your PH pen? I ask this because I had been lazy till last night and mine was off enough to give me some trouble...

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That was my first thought as well. Maybe some botanicare cal-mag + . I'm still leaning towards a general deficiency though. Purple stems all the way down to the soil.

It's made me wish that I had them.

Humanrob said:

I'm still at the beginning of the learning curve with diagnosing nutrient deficiencies and excesses. I suppose my less demanding previous lights let me get away with a lot. Recently I was reading @captainmorgan saying that GG#4 needs less nutes than most people think (sorry about paraphrasing), and that's one of my girls, so that combined with the stories of FFOF being too "hot" and burning plants, I was assuming this plant was getting too much of something... but now it seems that people are saying intense lights require more nutes, and it might be somehow under fed?

What do you think?

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It looks like too much lime at first glance. I think the Ca is antagonizing Mg and Fe.

Without any other info it looks like a couple possible things. Mag def,over watering. Diagnosing deficiencies and lockouts can be tricky and there are many causes. You have to be sure it's a def and not a lockout before adding anything to the soil or you can make it worse. If your mixing nutes and additives from different companies you can get PH problems sometimes. With the more intense LED light you would up your cal/mag and not always up your ppm's.

Humanrob said:

I'm still at the beginning of the learning curve with diagnosing nutrient deficiencies and excesses. I suppose my less demanding previous lights let me get away with a lot. Recently I was reading @captainmorgan saying that GG#4 needs less nutes than most people think (sorry about paraphrasing), and that's one of my girls, so that combined with the stories of FFOF being too "hot" and burning plants, I was assuming this plant was getting too much of something... but now it seems that people are saying intense lights require more nutes, and it might be somehow under fed?

What do you think?

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IMO
Doesn't need anymore nutes
Looks to be lockout . Tips are little burnt to early.
I can tell ya that I have taken ocean forest from seedling to harvest with straight water.
I would say your ph is to high and rec straight ph'd 6.0 to 7.0 water for week to correct it.

I'm trying something new... Botanicare Coco/Perlite mix on the bottom half, and FFOF Alaska Hummusoil and Worm castings on top, with some FF Marine Cuisine mixed in... This was in an attempt to get better aeration and drainage and less soil density at the bottom of my smart pots by the end of the run. Trying stuff out.

I have not tested PH, have a cheap meter that was entirely inconsistent so I stopped using it. I did test my water a while back, and its at about 6.1 IIRC.

As I write I know I sound incredibly sloppy about all this, but I hadn't had any problems before I recently, so I was living by the "if it ain't broke..." theory.