Guys please what’s happening to the plant

dank'd

dank'd

Well-Known Member
Jjgrow420 said:
Won't catch me clicking rando links sorry
Click to expand...
this is rollitup post i am linking to so no worries but here it is quoted:

"
The most nutrient issues we see with LED's are caused by a too high vapor pressure inside the leaves.
With HPS/MH or CMH bulbs the optimal ambient conditions are 25-26°C and 50-55% humidity cuz the heat radiation will heat up the leaf surface to ~28-30°C which is the optimal range for photosynthesis. These bulbs have up to 25% infra red in the range ~800nm. Plants are used to it cuz the sun has also IR and they use it to regulate certain processes like stomata breathing.
LED has no infra red and we need a higher ambient temperature to get the leaf surface temps in the optimal range. With LED ambient temps are = leaf surface temps(LST), with HPS it ambient +3°C.
Plants under strong LED light can not adjust the transpiration and we have to regulate it with ambient humidity to get the VPD in a healthy range.
But what has this to do with your calmag issues?
It is because when the humidity goes down the VPD inside the leaves get higher and the plants transpire more water than usual. With more water the plants also take up more nutes, especially calcium. And these high amounts of calcium looks out other metals like Mg, Fe, P and K. So yes, its because of calcium but because of too much nlt too little.

There are two ways to deal with it.
1. Lets say the VPD is 25% too high for the current plant stage. The plants transpire 25% more water and take up 25% more nutes. If you lower the ppms by 25% you can normalize the nutrient uptake but they can further use 25% more water.

2. the 2nd way to deal with it is to increase ambient humidity inside your grow room. The VPD is regulated by the relative humidity and the lower it is the higher the pressure to transpire water. With HPS and 25°C 50-55% is okay, with cold LED light and 28-30°C we need 60-65% humidity to keep the plants happy.
Below is a chart you can use.

Cutting nute strength and calmag in half worked out best because you did instictive No. 1. and have lowered the nutrient strength.

Its not so easy to maintain a good humidity the whole day. Especially in the dry month. A small atomizing humidifier just big enough for your room connected to a Sonoff TH switch timer(13$ incl. temp/humidity sensor) costs maybe 50$.

Indeed cannabis seems to need even more magnesium under strong LED light and too much calmag in the wrong moment(too high VPD) can make it even more worse. Plants would take up even more calcium this way.

Final conclusion...
It's actually no nutrient issue, it's a VPD issue caused by too low ambient humidity. Reduce your exaust fan or run it stop and go until the humidity is in the according range. Young plants and seedlings want 70-80% humidity(0,4-0,8kpa), plants in veg and early flowering want 60-70%(0,8-1,2kpa) and adult plants in the full flowering stage want 50-60% RH(1,2-1,6kpa).
The higher the VPD the higher the nutrient uptake and transpiration.
VPD Chart -1°C Leaf Temps.gif
I don't know your system but for your next nute soup I have following recommendation.
Add ~50ppm epsom salt to thw water first before you add your main fertilizer and if you have add some liquid silicone or horsetail extract too. Kelp, humidic acids, carbohydrates, myco's and other stuff can still be used but it would also work without such fancy stuff."
Pretty sure when you keep your VPD in a good range you don't need calmag. A bit more Mg in the normally used nutrient mix is already enough. Better two times too high humidity as one time too low."
 
amneziaHaze

amneziaHaze

Well-Known Member
I never seen a plant show defficency because it wasnt humid or was too humid...
Too humid is almost imposible never seen somebodys house be 80+ alll day long.but even that wont bother her just easy mold. And too low makes her piss water more or at max start to get blisters from too much evaporation.non of that will make her just stay nice and normal and lose color
 
dank'd

dank'd

Well-Known Member
i have. mh in blazing hot tent mid summer with no ac...

plants grew just about stellar during veg, but the heat stress crept in in flower big time

but most importantly the ambient temps were well over 27°C so nothing came out with any thc

can corroborate on the led also, a friends tent is super hot and humid and everything grows fast (in veg at least) but the heat stress is showing and it reaks of mildew
 
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dank'd

dank'd

Well-Known Member
and in winter when humidity is zero is the worst with led ime and many others experience. plant killer. never happened under any other light

it's all explained in the post i quoted above
 
Jjgrow420

Jjgrow420

Well-Known Member
I could agree with some of what is said there.
It's likely the ops room is too cold. No info on temps or anything so everyone's kinda just shooting blanks in the dark answering his questions imo
I've never been anywhere in the world where the humidity was 0
 
E

Everytimefoo

Active Member
amneziaHaze said:
I never seen a plant show defficency because it wasnt humid or was too humid...
Too humid is almost imposible never seen somebodys house be 80+ alll day long.but even that wont bother her just easy mold. And too low makes her piss water more or at max start to get blisters from too much evaporation.non of that will make her just stay nice and normal and lose color
Click to expand...
My grow tent with ebb and flow table, and resivoir hits over 80% when the lights are out. I water 24 times a day as i have a cover over the top tray with holes cut for the pots so the roots are suspended in there and need watering every hour. I have to have my inline fans turn on for 30 minutes or so every two hours to bring the humidity down from 80% and up to under 50%.
 
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