Ok, I am not a soil grower, but here are my thoughts.
If you are seeing the color changes, it is global (not just one leaf) then you probly need to take stock and get to the root of it.
Get it? Root of it (thank you, I'll be here all night).
So lemmee welcome you to
KILLBUD'S KLINIK
1.
Overwatering.
In soil you don't have the benefit of airstones, so too much water robs the roots of oxygen. The treatment for this (paradoxically) is soaking the plant in H202 enriched water. Do not do this unless well coached. Overwatering is a problem for people with too much luv.
The soil is boggy and may stink. You can get brown spots, yellow leaves or both.
A note on older leaves. Look to your revered elders One thing to note is many errors hit the big (older) leaves first. Why? B/c they are the resevoirs for crap
and the plant will use their stores of nutes to preserve new growth.
So too much nutes, end up in the fan leaves. Too little of something, out it comes from the fan leaves.
2. Overnuting. IMHO this would be #1 on a list for hydro problems (usu the root o2 is well covered so overwatering is not a problem).
Wilt comes first (altho most people miss it) b/c the plant is getting 'pruned out' from relative lack of water.
Following this the newer leaves will turn yellow
(pic1 and 2) , and you will see that junk precipitate as 'rusty spots'. It can resemble the interval chlorosis they talk about with Mg.... You can take an overnute prob and make it worse if you add more stuff to your solution (just like I did).
3. Nitrogen Deficiency
Doubtful. If you are using any kind of grow mix app. for MJ you will have enuf N. Usually the prob is too much, not too little.
However, N def will hit older leaves as well, but it is a general yellowing The plant will try to preserve growth and draw N from the res leaves.
How do I know about N def? Because I listened to a dude tell me my plants did not need nutes for the first two weeks. Of course his gig was soil and mine was hydro but one size fits all right?
The plants just cannot grow. They will lose green until they are a bright fluoro yellow.
(pic 3). Coincidentally it was at this moment when my entire grow was threatened that I met my friend. It was wild. He taught me how to nurse that plant back from the dead with careful foliar feeds, reduced light (to limit growth for a bit). You can see the green coming back into it, like a movie in reverse. It was coooooool!
(pic 4)
Numba 4: Mag def.
This is one of the most over-diagnosed problems on these and other boards. Usually what people are dealing with is overnuting.
However, Magnesium is the only metallic element in the chlorophyll molecule, which is responsible for the green in your foliage and photosynthesis.
Mg you will get yellowing of the older leaves first. (*)
My abbreviated story and why you can too
BTW, I like your spunk. So if you are still awake.. here's the deal...
I was a freakin' brown thumb before I got into pot. Everything I touched died. My houseplants turned to shit. I thought my girlfriend had some plant mojo I didn't b/c she could make them grow.
When I got into weed it was a for a friend who was dying of cancer. I didn't have a lot of room for error. I knew my skillz sucked so I did what I do for everything and just learned. the. shit. out. of. it. Anything worth doing well is going to take some hard work and passion, gf.
The appearance of my teacher was fortuitous. A virtual kid 10 years younger than me, but we've became fast friends. I've now innovated on my own so now half the time I teach him about what I'm doing. We exchange ideas... it's a very didactic very cool experience. A spontaneous poem!
"He looks like a hippy,
I look like a cop.
Together we grow herb
to make yer panties drop!"
(BTW, when you see pic three, that was the day I met him, when the plant was completely yellow and all was lost...)
The plant sense comes later... it's just going through all the hair yanking and f*ck-in-up stuff. You are learning what not to do and who's advice to trust.
It's why I post my errors. It's about honesty and the learning process. Geez have you been reading what I'm going through? (and I think I'm a 'pro'.
)
Be wary a bit of forums. I like places like this... but I have gotten some very baaaaaaaaaad advice, even from experts. Chew on it, question it, improve it.
Ok this is enuf ramble to add another page to your journal. But I hope it helps.
It's just about learning. You are def going to be cool if you are into this.
(*) BTW, if you are a hydro guy reading this, NEVER NEVER NEVER use the 1 tsp/gallon of epson salt to treat Mg def.
It will literally soak your plants in a solution with salt the strength of sea water. Do not do it! You have been warned!
