First time grow I need some advice.

First time grower here I have a couple questions if anyone can help me out I have some indica plants growing indoor inside a 4x4 6 tent and the bottom leafs are starting to yellow burn up also some plants are growing slower and faster then others 75% of them are 36inchs and the other 25% are about 18-19 inches I'm using organic a and b to feed them with a ph level of 6.5 - 5.0 with a 600w light about 3 months then been going now also when should I start to flower?

Pictures speak a thousand words!

Bottom leaves yellow = That is normal.
Some are growing slower = Are they all the same strain? From seed, Fem or straight run?
When to flower = How tall do you want them to get? The 36 inch will add maybe 50%(more like 25%) and the 18-19's maybe 25 to 50%. Could guess better, but I don't know what exact strain they are.

it depends on how much yellow is happening. a picture is really needed. Never let your soil dry completely and if it does use plain water first to moisten soil first then feed. as for growth diff dotn worry unless they are are clones form same mom. I planted 5 BB and 4 mystery. 1/2 of them are 1 node ahead and leaves are 2x as big as some. this si why we plant more seeds than we need so we can find the best female from a group, you want a fast grower but also quality/taste so some times you will have a few mothers till the harvest is done and you taste them after curing then you will know which one to keep. Me i will give up a bit of yield for taste and affect. it takes time to find your mothers to keep.
Peace and love

Yellow burning? You are over feeding them! This is a common noob mistake! Flush the soil with 3 parts ph'd water per gallon of soil and watch how much you are feeding them!

Bsd, why are you yelling at this guy, he's obviously new, you learn from mistakes.

the plants are all clones from the same mother also the name I was told is og ghost strawberry cough I have 21 plants do you think that's to many under only one 600w light what do you think the yield will be?

here is another pic

Okay flush with water asap use about 3/4 gallon dont use cold or hot water close to room temp. you have nute burn bigtime. after the flush cut your nutes in 1/2 from what you was using and make new nute water and feed them with 1 cup you will have run off allot but you need that so do this in a sink or tub that is clean and sanitary.
love and peace

also what are you feeding them? what dosage? what are your light time right now? maybe some sueprcropping can give you more light to lower part of plant also. dont cram them to close either

They actually look real nice-- Good job!

I would say that you are over nuting them a bit. I don't think you have to go through a heavy flushing though; if growing in soil, just use plain water the next few times to the point where you get some runoff.

The biggest problem you have, my friend, is that those plants will be beasts! 3' tall and under a 600w, and you haven't started flowering yet? I would recommend you flip now and get ready to wrestle with those for the remainder of the grow--- hope they don't stretch much for you.

I use dutch nutrient formula 10cc for every 2 liter's of water the light is on 24 7
After flushing them they should be fine I don't see any more damage showing up also humidity is always at about 50-60 % and temp is 70-80

They might stretch but I'm gonna put 4 feet bamboo sticks in them all to keep them up what do you think the yield will be if I flower for 3 4 months

You will have to keep your air circulating to provent mold. But if you stay on target, you might pull close to a pound, I would guess (sooo many factors, though).

Dude... Your grow looks fine...
That first yellow leaf, it's just an old leaf...
Looks nice and green...
Keep up the great work...

So a pound for all 21 so close to an ounce a plant or you mean each plant a p

also the stems some are straight and double even triple this mean anything

double

straigh

the double triple stem doesnt mean anything except more tops with more branches. i think he means total yield. i can say the plants are looking good on top.