Glomus said:

Yeah actually it looks like maybe a phosphorous deficiency. Also maybe a secondary deficiency like zinc or iron. Since you are not feedin anything to it, depending on what your soil is amended with. Are you inoculated?
Unless you are using RO water you should have some cal mag in them. It could have something to do with a cal mag deficiency. L amino acids will chelate CAL/MAG in the soil and water if you think you need it. Kelp can help with that too.

I can see the leaf tips are burned so its most likely lock out or a PH issue. Dude I hate LEDS

Click to expand...

SoHum soil is super nute dense so I’m cautious of adding any additional nutes until it’s depleted. According to their charts I have a couple weeks left on it.
Sorry I don’t understand the inoculated question.
Can I ask what nute burn you’re seeing? In the past I’ve had nute burn as browning and curling on my leaf edges. These plants aren’t looking like that, they are darker green on the edges which I was told was from the high level of nitrogen in the soil.
Black dog LED has an info page on not mistaking phosphorus def for LED UV exposure, but I’m cautious to listen to a company who’s selling you the light lol
I’ll try some cal mag, I was cautious with it before because I was told it could be causing my purp stems from my first two grows.

Homesteader said:

I have high intensity LEDs and can tell you that I am almost positive even without looking at the plant that it isn't a deficiency but a large production of anthocyanin caused by blue (and or red) light. You have a lot of blue in that light recipe. Anthocyanin acts like chlorophyll in that it is a pigment and will show on stems and branches that are hitting the light.

Click to expand...

Is that an issue? Will it cause a reduction in harvest or even potency? I figured it’s light related since it only turns under that light for me.

Nope it won't do anything that you will notice. It will only happen to strains that have the anthocyanin gene to express. Some strains even under heavy red or blue will not produce the color.

Homesteader said:

I have high intensity LEDs and can tell you that I am almost positive even without looking at the plant that it isn't a deficiency but a large production of anthocyanin caused by blue (and or red) light. You have a lot of blue in that light recipe. Anthocyanin acts like chlorophyll in that it is a pigment and will show on stems and branches that are hitting the light.

Click to expand...

So we can use the stem color as a guide of sorts?

A guide for what riot? Not following

Homesteader said:

A guide for what riot? Not following

Click to expand...

As a quick visual indicator of too much/not enough light, too much/not enough nutes, etc. I'm not saying that non-green stems can be used as a visual indicator, I'm asking if they can.

ritoMox said:

As a quick visual indicator of too much/not enough light, too much/not enough nutes, etc. I'm not saying that purple stems can be used as a visual indicator, I'm asking if they can.

Click to expand...

I hope so. I just did a small rinse on my soil grow. Stems were suddenly turning red a week after a full dose of Age Old Fish and Kelp. I'm in veg and those top 2-3 inches....?

Stems certainly can turn red or blueish/purple when pH swings (from cold often) prevent P from entering. I run a lot of 660nm red in my lights. (like 33% of my recipe) and you can tell by looking where the plant is not getting light under the stems and in heavy foliated areas. If that darker area is purple still then you probably want to check pH but if it looks like a sunburn, I would just let the worrying go.

Late 70, buddy growing Northern lights strain. After reading and seeing pics in high times, I mentioned loving the purple haired buds, wished I could get some.
He said, "can do". A little over a month later, he had purple haired northern lights.

He simply turned his ac down lower than normal to achieve that. Had nothing to do with inefficiency, although deficiencies can give same results, as some strains do.

Indoor growing is about manipulating mother nature, ie creating blue spectrum from the spring sun that is farther from the earth, growing or vegging,, metal halides hit that mark then and now. The sun rises further east in the spring in my location and nears closer as days pass. Late summer the sun rises alittle east south east and the days are getting shorter and sun moves further away and the spectrum is orange/yellow, hps and magic is in the air. Budding or flowering is in progress. Early cold to an outdoor grower produced beautiful buds of color. Growing is simple earth science, I still use nothing to grow under leds, ph if needed. No mixed soils, straight coco and a little something for bugs, jacks nutes, no test equipment. The light is still the most important part, then good genetics.

I have (2) CLW SX500 IN A 3X4. Purple stems every grow, every plant, but only on the light exposed sides. Never a problem. Anecdotal, but consistent in my setup. Soil, 5gal AirPots

So have you turned it over to view mode and looked at your stems?
It's actually the reflected blue spec lights showing ....
put it under white light or pull it out of your tent.

I thought the same my first run with a pair of CLW SS 550's