Where do I put the prp file to make the foilage work?

Inside the data_***/Worlds/***/world1 folder

OK, that's where it was. But it didn't work.

Do you have all the files your .prp file calls for in their respective locations? (MSHs and TGAs go in the msh folder whereas ODFs go in the odf folder)

It doesn't call for a TGA, but I must have missed that. I'll see if that's the answer I need.

EDIT
It still doesn't work.

It's not working because simply you don't have everything. Open up the ODFs your .prp file calls for and look for the MSHs/TGAs it needs. Open up the MSHs that your .prp file references and search for the TGAs they use. Unless you haven't applied foliage to your map yet, that could be the problem. Or maybe you're applying the wrong unused layer(s)?

I have the editor_grasspatch, which doesn't have a TGA.

The texture it uses is determined by an ODF file(s) referenced by your .prp file. Do you have these ODFs in your odf folder?

The PRP says that I just need the one ODF: nab_prop_grass.odf
The ODF says that I just need the one MSH: editor_grasspatch.msh
The MSH doesn't have a specified TGA. I'll post the PRP code below.

nab_prop_grass.odf TGA it calls for is nab_grass. So were you getting black rectangles on your map before or plain nothing?

Black rectangles.

Can't find nab_grass.

Ah, so it works partially. There's a nab1_grass.tga in the SWBF1 Naboo world assets in the msh folder. You can rename it to nab_grass.tga if you want.

I don't have the Tools for BF1.

Oh, I just assumed you have the assets for SWBF1 because that .prp file doesn't appear to be anywhere in the SWBF2 assets. You'll just have to use a grass texture from Yavin or something then.

I tried. It didn't work.

Why isn't it working? What did you do? Did you find an appropiate Yavin grass texure, rename it to nab_grass.tga, and drop it in you world's msh folder or what?

Well... actually no. I'll try that. I hope it works.

EDIT
Success! Thank you, AQT.