Whenever I paint the grass on a slope, it only paints the outer edges (see screenshot below). Is there any way to fix this? To me it looks ugly and makes beautiful houses not so beautiful. I have all the stuff and expansions.

You might try painting over those areas again. Changing the terrain can alter the terrain paint at times.

I did. It does not help.

Some terrain paints will fill an area on a steep slope better than others.

Other options are to use the "moveobjects on" cheat to place boulders, shrubs, flowers, tall grass and whatever you want on and around the slope. Works best to use the cheat with the "boolProp snapObjectsToGrid false" cheat.

Or, you can use something like tbudgett's retaining walls , here on MTS. I have only been using the retaining walls for a couple months but wish I had found them sooner because they are so very wonderful and give my lots a more finished look that is classy.

For my poor sims, I only use the cheats to cover the slopes.

That is good advice. I will try that tomarrow when my eyes are not drooping (it's 12:30 am here)

Just keep using the terrain paint tool with circular or left-right motions. That's what I used to do and it got rid of those marks easily. Use the largest circle. (Spraying the terrain, removing it, then respraying it also works).

Ok, thanks.