How to use nuterints

I'm going to get some nutrients for my plants that are going to be in fox farm soil. I want to get Jack's classic , but I've used the new AN nutrients 3 part grow mirco an bloom. When I used this AN stuff it burnt my leaves but yesterday I used some on my plant that's flowering bc its tricomes were growing really slow an when I look at them this morning they looked like there were way more then before. I'm not real kean on how to use this stuff, yesterday for the first time it worked on my flowering plant. Should I only use nutrients on plants that are or have been in soil for a long time An aren't getting any more nutrients from the soil alone? I feel like that's why I got more tricomes bc the soil is all out of good nutrients.

When I first started using this new AN on my plants before they were flowering it was fucking them all up, turning the leaves, yellowing the leaves all kind of shit. But like I said the flowering plant got more ticomes from giving it a little. I just don't think I'm using it right my plant vegging plant's.

FF has a lot of nutes in it already. Plenty for a couple weeks at least.

Wait so your saying that soil loses it's nutrition that fast? Holy shit no wonder why my plants are not holding together that good. They always look droopy an shit. Before when I used AN I was using it on my plants that had new from miracle grow soil an when I added any nuts it would mess them up bad. I ended up reusing my soil this time an they have been doing good but not perfect just kind of slow, but when I used some nuts on my 3 1/2 month plants that been flowering that long, it made the tricomes explode. This must be my problem maybe?