HELP!!!!!bottom leaves dying on veggin plants

I need help. the bottom leaves on my plants are all curling up and dying, it's slowly moving up to plant as by yellowing the leaves. It only started once i switched light cycles, to a 12/12. i thought at first that it may be a phosphorous deficiency so i switched ferts and it's still doing the same. i was using a plant prod 20-20-20 mix and i switched to a plant prod 15-30-15 i also add a b vitamin and a bit of epsom salt. i tried uping the nutrients but now showing signs of minor nut burn. i am currently flushing my medium and hoping something good will happen. I just don't know what i am doing wrong. can anyone help pls and thank you.

wish i could help more but i would never grow plants that big in, what ? 3 gallon soil ? good luck, also on the next run with the same square feet your using for those plants you could try growing maybe 12-15 and maybe up to 20 plants about a 1-1 1/2 feet tall and concentrate on the cola, plants are always real healthy and that age and when you get good at it you can get 1/2-1 oz per plant...

yeah this is my first time growing, i'm going to do alot of things different next time. i just wish i could figure out why this is happening, i just don't want to lose any

my bet is those plants are root bound, nother words your pots are to small for the root system in side the pot. almost put money on it. transplant into bigger pots will help.those pot look small what size are they?

yea no dout root bound

i able to transplant them at this stage??

I don't think your rootbound. Up-potting now would be fruitless anyhow, they don't grow roots very well once in 12-12. You need to give it some nitrogen. Give it some 20-20-20, and then switch to a 10-30-20. It commonly happens when you switch to 12-12.

Check out Uncle Bens thread :

https://www.rollitup.org/marijuana-plant-problems/158144-never-ending-abuse-phosphorous-bloom.html

You can put them in larger pots at any time. I had to do that to 2 of my outdoor plants last year during their last 2 months of flowering. Yes, the roots filled up the new pot very quickly and my yeild was great. I also gave them a bit of extra nitrogen and hydrogen peroxide to help with this.

Your lower leaves are dying because they are older, and dont get as much light, so the plant will concentrate its energy on leaves that produce better. If it bothers you that much, and if you have the opportunty, start to bend your plant over. It will take about 3 or so days of slow, incremental bending to get it to lay down, but youll find that the side nodes will become a lot more populated and, oh my, more and bigger budsites.

LST and FIM are your friends.

thanks everyone for the advice, i hope to produce some big beautiful buds, i'll let you all know how it goes

by the way its movin up the plant
i would say its a problem with n aswell

Sorry sister, key phrases here, "last two months of flowering"- they usually take two monthes to flower.(8 weeks)
And outside....- probably not even at 12-12 yet. they'll still have time to root.

trust me, I put 5 mature plants that were in 1 gal pots into 5 gal pots and immediatly put them under 12-12, they didn't grow much, neither did the roots.
You need them roots to find new ground. Word.