How much and what type of fertilizer you give ?
@ConorDash
I use Green Dream organic pellet fertiliser on all my trees (ones that are being fertilised any way), a sprinkling of that as a thin top layer on their substrate around the pot. Then every weekend I water with liquid fertiliser (dosage is the guided amount it says on the bottle, for potted plants), I use all purpose miracle grow liquid fert (diluted in water), and also a cap full of seaweed extract (helps with a full green colour in leaves).
My fertilising schedule and which ones is fairly new, this year. I only started bonsai last year March, not been in it long, just over a year. So I can't speak to how well it is, but it's not killing anything... so that's a start!
This is my olive. You can see remnants of grown hard looking stuff sitting on the top of the substrate in the first pic, that the organic pellets. It could do with more being put on very soon but there will be a lot broken up in the pot and remember the trace nutrients it gains from fertiliser takes 6 weeks to move up in to the tree (if I remember that correctly).
For me, it's all about growth,branch development on this guy at the moment. Repotted this spring, it needs time and vigorous growth. Currently growing slowly and not much... but maybe that's cos I repotted at the wrong time (as pointed out by Adair M lol). I cannot get it to back bud and it desperately needs more branching from the trunk so at the moment, I am using 2 branches that are coming out of the same location as 2 others. Usually this is a bad thing but I am wiring them so they exit as far as possible to hopefully make it work in the future. Hopefully makes sense.