Funny, I have some leaves clawing. Just noticed that with the two plants that aren't flowering. Does locked nitrogen cause yellowing and crispy leaves? I think I've dealt with that before.
Yeah locked nitro can cause yellowing, and low calcium can cause locked nitro.
When Ca gets low, which makes Mg high in ratio, N gets locked by Mg and she yellows.
That causes stress and immunities drop. Now the plant can't tolerate the same level of light, so the leaves get light poisoned, and in a week or 2 crispy leaves show up. CO2 intake is also restricted from the hot leaves closing the stomata, and it all magnifies.
Most folks use Calmag as the 1st goto, because it fixes darn near everything, and the yellowing stops, but it gets replaced by the claw because the Ca released all the N on contact, and that nitro rush causes nitro toxicity. AKA The Claw.
The nitro toxicity is temporary. It's done before you even see the claw, but the clawing usually stays forever like a scar. It's ugly but otherwise harmless once corrected.
The VPD numbers are going to be most useful after the plants have been fed and watered and have time to take things up. Right?
VPD, like brix, should be taken at about the 10 hour mark.
At night, plants raise leaf temps above ambient temps to flip themselves into respiration, and use all the sugar from the days photosynthesis to grow.
At lights on they flip back to photosynthesis, but if they still have unused sugars, they will waver back and forth between photosynthesis (transpiration occurs here) and respiration ( photorespiration during lights on), and will do this by fluctuating their leaf temps, so if you zap a leaf earlier than 9 or 10 hours after lights on, you aren't nescessarily getting a true reading.
By late in the day photorespiration is done and she's running full bore making sugars again. That's when brix is highest, and that's when she is running her hardest.
You want VPD to be set to this point in the day, otherwise if you set it earlier she may be running too hard late in the day, and stress occurs. If you up VPD to 1.45 at 3 hours after lights on, it may rip to 1.6 or 1.7 by the 10 hour mark when she's running hard. So you make adjustments by late day readings.
Thinking I should do those numbers tomorrow as well, when I do the brix test.
Take temps any time, but adjustments get made at the 10 hour reading only, and brix is best done then too.
Right now, I'm getting VPD at .98 -ish on the non flowering, and 1.2-ish on the flowering plants in the back.
How long after lights on was this. 10 hours..... 10 hours....
My head is spinning.......
That will stop. I'll keep repeating. Every time I do you will take 1 more step. You'll get there, everyone does
. If you've been lurking in GeeSpot you must have noticed the repetition
Once you get out the other side it becomes easy, because it's actually the basics, and your plant reading and troubleshooting skills will really increase. Only to be exceeded by your ability to avoid it all in the 1st place because you are now the proud owner of the water stik, the ray gun, and the refractometer.
10 hours.... 10 hours... that's important. Don't hurt her. 10 hours.
But definitely do zap the leaves earlier and as often as you like. It's great learning, she has rhythm. It's cool to see. They do shit all day long.
The only way she can switch from producing sugars to using them is to fluctuate her leaf temps. She's flipping back and forth between O2 and CO2.
Don't panic when you see nasty numbers early, she knows what she's doing. She's flipping thru processes. Ones that don't need carbon need warm leaves to shut it out.
You just need to listen to her at the 10 hour mark is all. That's when you step in to help her out with VPD stuff. That's when the roots need to match the shoots.
Make sense? and yes I'll have to remind you. That's just how it works
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