Yellowing and dieing lower fan leaves.

So over the past few weeks my Pure Afghans I got free with my WW and Blueberry seeds from marijuanaseeds.nl I have noticed lower leaves have been yellowing until they are light in colour then falling off, or I have been picking them off when they are dead. It's only slowly happening but I figured it must be a N deficiency.

So today I bought 20-5-5 slow release fertilizer tablets. I have placed 2 into the soil and re-potted my plants into some new pre-mix/sheep manure mix. I feed them Canna A+B Flores at 2.5ml/L each once a week then in between I water with ph'd tap water. These are my second grow under a 400W HPS, vegged under UFO 90W LED after my first grow I over nuted some bagseed and firgured I'd use the free seeds before WW and Blueberry for more practice. The over nuted bagseed plants have been flushed and are slowly picking up again though.

As you can see the lower leaves and also curling up in the sides and looking abit funny. So, I'm just looking for some advice as to how I am doing and If I did the right thing with the slow release fertilizer tables with high N.

Thanks,
Skroatz

Pictures...

BTW they are flowering in at 4.5 weeks now.

need re-potting, also avoid the tablets and sheep shit, you dont need that much N at this time.

Thanks. Anyone else?

i thought in flower in Phosphrous needs to be kicked up

Agreed, those slow-release pellets are the worse thing habit you could get into. If you can, remove them. If you can't, remember not to use them again, in the future. The reason for this, is that you have no idea how much fert they are actually getting, making feeding a guessing game. Not a good idea, when growing a plant so sensitive to nutes. Agreed?

Anyway,...You plants are well into flowering, and for the lowest leaves to slowly yellow and die off, is normal, as the plant is nearing the end of it's lifespan. The rest of your leaves look kinda dark, actually, indicating a tad too much nitrogen.(hard to tell for sure, in the pics) The curling of the leaves, looks to be from the temp being a little high, or the heat from the lights, possibly combined with too much airflow and/or low humidity. Could also be from too much nitrogen. At any rate, I wouldn't worry too much. The plants look pretty healthy, so I'd say to switch over to a P-rich flowering fert, til the end of the run. Yes, you'll get more yellowing, but that's the way it works. Normally, they look pretty rough by the time they're finished, and won't be those lush green plants you saw while vegging. They're dying, remember that.