Ok this is, and goes, hard.
The concept resemble a lot of recursive functions, and seed planting is such a way to hide that. When it introduced 2 types of seed it suddenly became very tough, and the final level was another massive roadblock, but I managed to solve them eventually.
I agree with Dusty that the game needs more tools to visualize. In addition to 'one step at a time' button, I think the trees/plants matching with the color of the seed would be nice. Regardless, I had a blast playing this. I know this isn't a game for everyone but this is 15/15 for me. Awesome work :)