How do you tell genetic purple apart from phosphor deficiency?

[TheFertilizer]

I was looking at one of my plants and noticed at its base it goes from green to purple abruptly. It was grown from seed. The Platinum Girl Scout Cookies I have always seen have this dark lavender color, but I still have people tell me all the time it's phosphor deficiency. I have wondered if maybe this strain just wants more phosphor than is in usual NPK ratio amounts.

Anyway I thought it was weird and thought I'd share and ask why this happens. Also what's up with the barnacle like nubs on the stalk? They kind of just stop suddenly too. Again these are from seed.

 

[Weaselcracker]

You'll know if it's a P deficiency and it progresses. Leaves start looking unhealthy and dull, they get kind of stiff and dead and thick looking, and will snap off the stem very easily, along with all sorts of unhealthy discolouration.

 

[ChronicAffair]

The purple is a magnesium deficiency. Not phosphorus. Most deficiencies are micro issues, not macro.

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[Twox]

Your leaves look really healthy... Have they suffered some colder temps lately? I get purple streaks and stems during these colder months..

 

[Twox]

Oh ya, those little white bumbs on the main stem are just potential roots.. I think all cannabis plants do this, at least all mine do..

 

[MadScience]

That's the barrier between the root stem and the plant stem. You should fill that space in with dirt, those little white nubs will develop into roots.

fwiw your plant looks fine, way to soon to worry about a P def causing color changes.

 

[TheFertilizer]

Your leaves look really healthy... Have they suffered some colder temps lately? I get purple streaks and stems during these colder months..

High 60s are the lowest they see

 

[Weaselcracker]

Magnesium def can sometimes cause purple stems, as can P deficiency. But neither one of them always or even usually does at least in my experience. Either way you'd be seeing slow growth, and other symptoms. If there aren't any other problems going on them chances are it's just genetics.

 

[TheFertilizer]

Well, it's not exactly growing great, but Magnesium def. would seem even less likely because I've got them in FFOF and have fed them GH FloraNova, so should have plenty of nutrients available. Right now it's kind of just on the mend from me planting it initially into depleted FFHF. Maybe a little nitrogen toxicity going on, because they don't seem to like the amount of nutrients I gave them.

The front and center one is Blackberry Kush, and you can see it's doing pretty well. The rest of them are Platinum Girl Scout Cookies, and they are definitely varying in there condition. I don't know that the seeds I had were very stable, some seem to respond completely different to the same amount of nutrients than others. The Blackberry Kush is actually a week younger than all the other plants there, so I may have just irreparable stunted those.

I am thinking about cloning off the healthiest looking one (that's a draw between the one I posted and its neighbor) and just running a clone crop to try to keep the variables down because it's too hard guessing envrionment vs. genetics.