Nevermind... figured it out for myself and recompiled.

It's what I was looking for, but there's no mod options or settings to adjust the cost, or anything else... How do I make this not cost chemfuel?

It's working wonderfully. Thanks!

@Kearse I've pushed an update that makes fake plants use real plant's altitude layer. Can you check how the rendering works now?

The game renders normal grass under walls and trees over walls. Achieving that would also be nice, but that would mean having different categories for fake trees and fake everything else I think.

Regardless of the altitudeLayer I choose, this thing also always happens where bits of the fake grass render over the fake trees. See: https://ibb.co/6whS52m

By the way, all the grass and trees shows are fake/decorative from this mod.

So I played around with the <altitudeLayer> line and found that the decoration plants generated by this mod use the Building layer, which draw/render over the walls. See: https://ibb.co/hc9dPPp

This makes both the bamboo tree before and the grass behind the wall be drawn on top of the wall. So I changed <altitudeLayer>Building</altitudeLayer> to <altitudeLayer>FloorEmplacement</altitudeLayer>. See: https://ibb.co/gWWS6tK

This caused the grass to render behind the wall, which is nice, but also the bamboo in front, which isn't. Is there a way to solve this? I use a mod called Perspective: Buildings where you can adjust the position of things a little bit that succeeds with it (things north of the wall get "tucked in", things south of it render above it), but I have no idea how. See: https://ibb.co/HzyGXCC

@Kearse What exactly do you mean? Can you post picture?

Would it be possible to make the decor plants render under buildings and structures? Because as it is now, they render over furniture, walls, lamps, etc. unlike normal plants.

This mod is amazing, exactly what I was looking for.