How do I make custom crops with blockstates?

I'm trying to make custom crops, but I don't want to use multiple models; I'd much prefer to just use one block with different blockstates. However, the blockstates plugin doesn't work for plants and besides, it doesn't let me specify the name of the blockstate anyway.

I found this tutorial on reddit and it seems to work for some people, but it's written in a very informal way and I can't make complete sense of it:
https://www.reddit.com/r/MCreator/comments/11q6655/how_to_actually_make…

Could someone more knowledgeable than I explain it more clearly?