Surprisingly enough I don't actually think Botania adds anything you really grow, I mean there's ways of creating more mystical flowers but that's it. And yeah, literally very method of power generation except the daybloom, nightshade, and hydrangea tries to bring forth varying levels of automation challenges. Adding other mods simplifies things but botania is supposed to be able to automate (nearly) everything, lava acquisition being the main thing it can't automate iirc. The top tier generation systems are stuff like a flower that eats nearby cake or captures TNT explosions or consumes all sixteen colours of wool in a rotating cycle, the most complex would be the one that simulates a tweaked Conway's game of life nearby and generates mana based off how many generations certain cells took to make it to the flower.
The mod does let you automate nearly anything, but it often requires quite a bit of complexity to do so as it's all about individual parts.
Riskable's youtube channel has a bunch of videos of various more complex things you can do with it, for example their most recent. In it they automate the spectrolus which I mentioned above, it generates mana by consuming coloured wool, but has to take all sixteen wool in a specific order to generate mana, it'll consume any wool that you give it but only generates mana if it gets the next colour in the cycle, so they created a sheep farm to harvest the wool, a method of giving it in the correct order, and an auto-shut off system so whenever it runs out of one colour it stops until it has that colour of wool again. All with just botania and vanilla I believe.