Yellowing leaves, unknown cause

Okay everyone heres the deal. Im outdoor growing and my female plant is just flowering (best one is a male, damn) and some leaves turned yellow. I use the pesticide "Seven - grub killer" but i dont think its the problem. I have never fertilized my plants once, i used miracle grow slow release soil but its been longer than 3 weeks so maybe i should fertilize. I have been using super thrive in large amounts, i estimate 10 drops a bottle of water shared between 2 plants and one very small one. Maybe a lack of nitrogen? Plus i need to fert now to get big buds, i will be using miracle grow (i know it isnt high grade but its all i have) so what concentration should i use. Take into concideration the slow release things in the soil.

Thanks in advance.

if it is any help at all to know, the top leaves of the plant are thriving, lush and green, while the bottom ones are a lighter colour and dont look too lively, at least compared to the top. The leaves that yellowed were around the middle of the plant.

do not fertilize...sounds like too much fert from that damn miracle grow...start flushing instead

Only lower level leaves are dying? 3 finger and single finger leaves? That is normal. Seriously don't do any radical fixes. THAT is how you will fuck things up.

Stay on track...stay on course.

They are weeds...they will require you to fuck with them in order to die before they are supposed to.

always fertilize lightly. Having pre-fertilized slow release soil is a p.i.t.a. as you have no control.

In the future don't use that shiite. Use good potting soil which will naturally have enough nutrients to get your plant to the end of week 2 when you can start using veg ferts.