Chasing a second opinion on my sick plant.

This is my first grow, Amnesia x Skunk#1
Germinated in early November Shes about 35cm tall, Watering about every 3 days and using an LED Panel for light
currently sitting in a 4.5L pot with Searles Premium Potting mix.
I have not been able to pinpoint what is actually contained in searles products, they don't seem to provide much info.
The package says it contains slow release ferts for up to 4 months.
The ph reading is 6.8-6.9 Measured with an analog meter.

My problems started when we had a massive heatwave in December, reached 45C for a couple days in a row. I had not
started feeding by this point as the additives in the soil seem to be holding her up pretty well. But then
the fungus gnats attacked (I figure I was over watering them) Was able to get rid of them by slowing down on
the water and sprinkling some Cinnamon over the soil (I had heard cinnamon is a good fungicide)

After the gnats the plants growth slowed and she seemed weak so I stated with 1/2 Strength Thrive all purpose fert.
She perked up, and the top is growing fine producing new leaves and looking great, All the damage is happening
from the bottom up. The tips started to turn yellow soon after starting with Thrive, so I flushed the soil thinking
it was nute burn but the leaves started turning light green then yellow between the veins, eventually turning the
whole leaf yellow all while the tips continued to burn inwards, turning yellow and brittle then falling off. New
growth appears to start at the lower sections, but that's as far as it gets.

Looking through all kinds of pictures and posts I figured the initial yellowing was from N Def
so I started the Thrive fert on 1/2 again but the yellowing kept progressing so Im now up to full strength.

Going through all the charts and descriptions again it kind of looks like alot of things but it also doesn't.
There are no spots or blotches and no purple in the stems or anything like that. The burning just seems to be
uniform all the way from the tips inwards, sometimes they curl upwards sometimes down.

So now im thinking Zinc def and possibly calcium too?. There doesn't appear to be any calcium in the Thrive, and
very little zinc (0.004 as sulfate, Is that enough?) Im chasing a second opinion on this one because I fear
anymore of my thinking is just going to kill her :/

Okay firist of all get a bigger pot at LEAST 2 or 3 gallon pot, repot and use GOOD quality soil, not sure about the soil you are using now i would recommend something that works like fox farm ocean forest. A plant that small should not need much nutes with good quality soil. And lastly what king of led light are you using?? it might be too weak or might have it too far from the plant. Lemme know i will try to help

Is a bigger pot necessary if I don't plan on growing any bigger? I've only got a small space to work with at the moment. unfortunately there isn't much in the way of choices for soil out here, its either searles or dirt. I can get ahold of perlite and vermiculite so I'm going to try a soiless mix for my next plant.
The LED panel is just a prototype I made for a larger grow box I have planned. It has 150 Ultra-bright LEDS, (60xBlue 470nm, 60xRed 625nm and 30xOrange 605nm) Its sitting about 10cm above the top of the plant.

HC,
OK, I'll tell you what I think. When you had the heat wave and started adding more water, by doing that you dissolved too much of the time-released nutrients. And then you added the 1/2 strength feeding. Two things commonly happen when you over-fertilize...

The plant soaks up too much nutrient and becomes toxic. Leaf tip necrosis is classic nute burn.

The other issue is that the soil becomes saturated with nutrient salts and locks out nutrient absorption.

So your plant showing N and Mg and Ca deficiency does not mean that you aren't providing enough...it means that the plant can't absorb it.

So meanwhile back at the farm...you see yellow leaves and add even more nutrients...when the problem isn't lack of nutrients, it's lockout.

It could need a bigger pot and better soil. Certainly that would help. But stop overwatering and adding nutrients or you'll kill it for sure.

Because you are in time released nute soil...you can't really flush. It might recover...it might not. You've boxed yourself into a corner...
JD

Im also on my first grow, and really noob but i think i might be able to help by showing the effects of being rootbound. Thats what mine looked like about 3 weeks ago.I was waiting to see roots come through or by the drainage wholes, but it never happned(at this point it was 5 weeks old and really undersized(and showing similar signs). Eventually i was given some good advice and transplanted it regardless, into a 3 gallon pot.
This was 1 week later, the yellowing completly stopped, and it literally doubled in size.

Hope it helps, Jael

John dee gots some good points . it could be ph lockout , look like some nute burn for sure tho

you're killing your plant with kindness. if you stop it may bounce back.

Flush well with RO water and then continue the normal feeding regimen. Make sure you're using some cal-mag.