Red stem data

Moflow

Moflow

Well-Known Member
Here's some data to peruse in pursuit of the Red Stem Conundrum

Is it the light spectrum, the temperatures, the overall environment or genetics?

The red stems do not worry me in the slightest and the plants all finish up nice.

I'm at roughly 55°N in the UK
It's ok to use the Sun as a veg light but its no good for flowering were I am.

All plants are in the same soil and get the same food.


Plants outdoors
Candida CBD and Sensi Star original clones
They've been outside about a month in overcast sky with a large helping of torrential rain every day.

Candida CBD revegging, no red stems
20190621_131836.jpg 20190621_142733.jpg
Sensi Star original above, no red stems

The weather has been mostly overcast for a month or so, no sunshine to speak of.
Temps, avg daytime temps 15°C - 59°F
avg nightime temps 9°C - 48°F


Indoors in un heated attic under Samsung F strips 4000K, lights are on 24 hours a day.
Similar temps to outdoors
Sensi Star original and Royal Gorrilla clones
I brought them into daylight for pics.

Sensi Star original clone
20190621_145121.jpg 20190621_161141.jpg
Royal Gorrilla clone
20190621_144431.jpg 20190621_144458.jpg

And a Moby Dick under Samsung Hinflux lm301b diodes in tent
Temps ~12°C - 20°C No red stems to speak of.
20190621_163438.jpg

And last year outdoors
With exceptional heatwave, good temps and wall to wall sunshine
Sensi Star 2 clones with no red stems.
20180720_201635.jpg
20180919_142313.jpg
We were hit with a bit of a hurricane but it survived, Musta been the green stems...... lol

As a side note
Summer Solstice today so at 12:14 pm a break in the clouds appeared and I took a PAR reading
20190621_121439.jpg
 
nachooo

nachooo

Well-Known Member
Imho the red steam issues with leds is related to bad transpiration when using certain intensities of light ...I solve it when I follow a VPD chart.....in my case low temps, low humidity and too much led light is the perfect combination for red stems..If I add Mag, the situation is not solved..on the contrary is worst…
 
whytewidow

whytewidow

Well-Known Member
nachooo said:
Imho the red steam issues with leds is related to bad transpiration when using certain intensities of light ...I solve it when I follow a VPD chart.....in my case low temps, low humidity and too much led light is the perfect combination for red stems..If I add Mag, the situation is not solved..on the contrary is worst…
Click to expand...
I get purplish/red stems if I use to an excess of light not needed with higher temps. And mag def. Back light off and add some mag. Fixes it. Keeping temps in check as well. I agree 100% with you. When humidity/temp is outta whack with leds, red stems is almost a given.
 
Axion42

Axion42

Well-Known Member
At the start of my current run my clones developed purple stems, humidity was low (~40‐50%) and temps were 78°f during day and 72°f during night. Since then my temps are about 85°f during day with 65-70% humidity and 77°f at night with 65-70% humidity and all stems are green except the part that turned purple to begin with. Other than the enviromental change nothing else has changed for me. Running 6xHLG 288s with blue supplemental rails, using Canna aqua Vega nutrients with nothing else. I use my tap which is 150ppm rich with calcium and some mag so I don't need to purchase any cal mag.
 
Chip Green

Chip Green

Well-Known Member
Yet still, the question becomes, is there any measureable detriment to these pesky red stems?
This is actually a serious question.
It stands to reason that any plant kept in maximum optimal health, should yield better than, even a slightly unhealthy plant........er no?..

I would do a straight up side by side, Red Stems Vs Pure Green Stems, but that would be unfeasible, as I am highly unlikely to grow a plant with all green stems for it's entire lifespan.
It's just really not even necessary. For me.
At this time.
 
Axion42

Axion42

Well-Known Member
I agree, I've had almost an entire plant with purple stems fan leaf stems included and havent noticed any negative effects that I can clearly see.
 
Greengenes707

Greengenes707

Well-Known Member
"[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5655971/']Various factors, such as UV, visible light, cold, osmotic stress, and pathogen infection, can induce anthocyanin biosynthesis. In contrast, high temperatures are known to reduce anthocyanin accumulation in many plant species, even drastically in the skin of fruits such as grape berries and apples."[/URL]
[URL]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5655971/[/URL]

"The differences in total anthocyanin production among the four temperature combination treatments decrease with increasing duration of the light treatments."
http://www.plantphysiol.org/content/plantphysiol/81/3/922.full.pdf
 
Rocket Soul

Rocket Soul

Well-Known Member
We had a feeling our amnesia haze vegged with less purple stems under 3500k than 3000k but 2 separate environments so not a 100%.
3000k veg is slow for us, cant get them much over 10000lux for more than a day without purpling. Less problems in flower generally. If they purpled in veg they tend to be more finicky in flower. My growbuddy thinks its got something to do with maturity. He played around with temps/rh acording to vpd but no joy, but he might not have gotten it right simply. But even replicating conditions of a good veg run, sorta copying the environment of what worked, didnt do the trick.
More calmag doesnt seem to help, at least not in the pot but still not tried foliar. Sunlight seems to be the ticket: UV opens stomata and infra red increase transpiration. Also raising our ph (in coco) to 6.5 helped a bit.
Things id like to try:
- slowly ramping up and down intensity during the day, to get them used to higher intensity during short times instead of having to go up in intensity during the whole day. See if keeping the same DLI with ramp up/down as constant intensity conditions changes anything.
- Vegging with Vesta strips to be able to do spectrum tests easier, 2700/5000 k mix.
- Foliars: if its down to too much light for too little roots. Ive seen mentioned epsom salt and found references to calcium-25. I dont know if you can foliar calmag?
- Stricter tolerance with environment. Trollmaster is now available in europe and they have a VPD meter with logging.
@Greengenes707 you have the trollmaster right? Can you get a probe for temps/rh to get exact cannopy values? If your limited to temps at the location of the box (on the wall) its rather limited.

Anyone have any thoughts?
 
Greengenes707

Greengenes707

Well-Known Member
Rocket Soul said:
Trollmaster is now available in europe and they have a VPD meter with logging.
@Greengenes707 you have the trollmaster right? Can you get a probe for temps/rh to get exact cannopy values? If your limited to temps at the location of the box (on the wall) its rather limited.

Anyone have any thoughts?
Click to expand...
What made you think that is how it works?
http://trolmaster.com/content/?283.html

EDIT:
You should check out the other links I posted too... HIR...high irradiation reaction.
 
Last edited:
zypheruk

zypheruk

Well-Known Member
I always get red stems when growing in coco, never in compost or Hydro no idea why and it aint the cold as my temps never go below 22c. Now the red stems normally go back to green within a week or two in flower.
 
grotbags

grotbags

Well-Known Member
i cant see where the trolmaster hydro X does VPD, just standard humidity control. the trolmaster hawkeye will monitor VPD and has a smartphone app to log VPD ect but cant control a humidifier to actually keep VPD in check so pretty useless.
 
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