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Questions [Completed] Purple / Red stalks

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Ok so I’ve read multiple books and listened to hundreds of hours of podcasts and have learned quite a bit but I’m having trouble figuring out why my stalks are streaked purple & red ? I know this is going to require quite a bit of up front info regarding my set up so I’ll try to give a brief description. Growing in bagged soil (Roots Organic 707) with added worm castings from Colorado worm company, 5 and 10 gal fabric pots set up with Blumat carrots on a gravity fed reservoir. 4x4 tents using HLG 600R led lights. Mostly following the Build A Soil dry amendment protocols. My well water has extremely high ppm (1070) so it is run through a whole house softener and filtration system plus an additional drinking water filtration that includes an RO filter and several other filters and a remineralization filter that produces drinking water with 74 ppm 8.5 ph. I do add a cal-mag product to the reservoir and also add epsom salt to my soil drench feedings every couple of weeks. The girls look pretty good other than the purple/red streaks on the stalks , at first I thought magnesium deficiency and added the epsom salt to my nutrition regiment but not seeing any improvement. I also thought possibly genetics as 2 of my successful grows were from same breeder but this latest grow has 2 from Humboldt seed company and they are also showing the purple/ red streaks since flipping to flower. From what I can find in my grow books and on the internet magnesium and phosphorus deficiencies can look very similar so if anyone has any ideas I would love to hear from you. Thx

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SuperCropper SuperCropper April 27, 2022 8:06 am

Could just be genetics, bro. It looks to me like you have done about all that you can to keep your plants looking healthy. Perhaps the Humbolt genetics would like a little warmer temperature. I read your info question twice and I still don't see what your grow room temperature is kept at. Perhaps your room temperature is colder than what the breeder used when they cultivated this strain. You might want to check with the breeder and find out what temperature they recommend. Perhaps the Cal Mag will fix your issues in a few days.  You might have to turn up your grow room temperature to a more comfortable setting.

5 Answers

Welcome to Percys mate 🙂  Im pretty new to growing myself, think iv done about 10 grows, and nearly all of my ones ended up with purple/redish branches. I think it can be genetic, stress can cause it and sometimes the light can cause them to darken a bit like a purple sun tan but as far as iv seen it never does any harm. When I first started growing I wondered what was happening to my plants when I saw it but now I dont really pay any attention to it 🙂 

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When you see it in a young plant it is generally a sign of stress and an indicator to dial things in a bit more.  When it comes to later veg and flower I wouldn't worry about it at all.    It does seem to be a sign of stress but I have had plants stripe like that all the way through flower with no issues.  And hey, stress isn't always a bad thing for our girls.  😀

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You could be looking at some “sunburn” on those stems. Led lights can trigger a response on plants causing some reddish pigments in some stems. Usually if you look at leaves in brighter light the color is darker and on leaves that are constantly shaded the red is very light or non existent. Red color can also be a deficiency but most often it’s a reaction to the LEDs.

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They look pretty healthy apart from the purple/red lines. I have had this happen to many grows. But it was genetics. If that's your only problem on the plant and all the environment is within range. I wouldn't stress that much about it. When you use Epson salts a foliar feed with it will work wonders and the plant will absorb it a lot easier.   Best of luck Thumbs Up  


is caused by the intensity of the led lights... have a look on the underside of leaf petioles that are red on top - green underneath.. same with stems/ branches that receive more light... 

moving your light higher may help at a loss of intensity but gain in footprint  uniformity

as mentioned before.. sunburn effectively.. unless the whole thing is going red, top and bottom

if overall the plants look fine, then then are fine .. how would they differ overall if there were no purple streaks on the woodwork ? pretty much the same

its rare plants dont get this under leds... not entirely sure if its one that needs solving !? but i get where u'r coming from.. rather not have it at all

some strains dont get it so much.. is this because they are more tolerant to the led intensity? i suspect so, whereas others less so 

2p worth Smile

happy growing 

#up the mag 

Time to pop some more beans 😗

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