Problems with lower leaves dying off..

for the past couple of weeks my plants have had about 4 or 5 lower leaves turn yellow and die off...I was at first thinking nutrient problem, but my leaves aren't really showing unhealthy signs, it's just that a couple of leaves die from here to there. Is this normal? I've included a few pictures, quality isn't too great, but maybe you can tell me if this is a bad problem or not? It's not seeming to affect the rest of the plants, it's only happening to some of the lower leaves, and new growth is fine; preflowers are showing on one plant :)

I know that's a lot, but bottom line, is this a problem that's serious, or is this something that happens?

What week are they in? If in flower it is fine, if in veg beef up the nitrogen it is most likely a deficiency.
Adieu

I'd say around five or six...No flower yet, still vegging. I did read a bit and was thinking maybe nitrogen def...It's been nearly a week since last nutrient(miracle grow 15-30-15...But I indeed do have purple stems on three or so of the older nodes. The newest one stems are turning nice and green. But yeah, do you think it's worth a try giving them a bit of nutes and seeing if any improvement comes from it?

Yes, I think that it is worth it. That MG has time release properties that don't allow all of the nutes out until they hit a particular temp.
Adieu

that MG is for flowering you need high N like 10-0-0 you have a high P which is the center number it will not do what you want it too get some high N and it will solve your problem

You can get a 6-3-8 or something like that too, I learned that some veg nutes aren't always highest in N, but I like to have a high N property just so I don't have a nitro prob myself, but yah what Envision said as well should do you.
Adieu

See if the local garden store has a bottle of Alaska fish ferts for veg. I wouldn't use the flower IMO, high traces of arsenic, yuck. Don't trip many organic ferts have the same thing, just different amounts.
Adieu

Thanks for the advice guys, and I'm watching it hoping for some signs of improvement on the deficiency..Still continuing growth.

I was kinda wondering what one is to look at when determining when to go to 12/12...Is there a certain height or anything?

Here's some new pictures..quality isn't wonderful, but you can see them.