Dry grass, scrub, and a few marks for interest
Okay. Last lesson you got sky, mountains, and foreground laid in, in that order, and if you stopped there you'd already have a decent little painting. Foreground is where a lot of people either get precious or get bored. We're going to do neither.
Foreground is closest to the viewer, which means it's the one place your brain will beg you to add detail. Individual blades of grass. Every rock. Resist that. A few confident marks read as "dry grass and scrub" way better than fifty careful ones do. This is the whole lesson, honestly: less is more, but the less has to be decisive.
What we're actually doing
Your foreground wash is probably already down from last time, some warm yellow-green-brown mix, mostly dry now. We're going on top of that with dry-brush marks that suggest texture without drawing every stalk of grass individually.
The brush matters here. Grab your round brush, the same one you've been using, but this time you want it almost dry. Load it with paint, then drag it across a paper towel or the edge of your palette until it looks like it barely has anything left. This is called dry-brushing and it's the opposite of everything I've taught you so far, where we've been chasing wet-into-wet. Here we want texture, not blend.
Drag that half-dry brush across your paper at a low angle, almost sideways, not straight down like you're stabbing it. You'll get these broken, scratchy little marks where the paint catches the tooth of the paper and skips in spots. That skipping is the whole trick. It's what makes it look like grass instead of a green smear.
Do this in clusters, not evenly across the whole foreground. Real dry grass grows in patches, thicker in some spots, thin or bare in others. Leave some of your base wash showing through untouched. That contrast between marked and unmarked is doing more work than the marks themselves.
Color, and a word on mud
I like a mix of burnt sienna and a little of whatever green you've got, sometimes with a touch of the blue from your sky mixed in to dull it down. Your foothills in real life, especially by late summer here, are not green. They're this gray-gold-brown. If you paint them true green you'll get a lawn, not a hillside.
And look — if your colors get muddy doing this, that's fine. Genuinely. I know everyone panics about mud, but a little mud is exactly what dry August grass looks like. That grayed-out, not-quite-one-color-or-another mess is realistic here. Learn what makes mud so you can make it on purpose instead of being scared of it happening by accident.
A few marks for interest
Once your grass texture is in, add three or four small deliberate marks. Not grass, something else. A fence post. A dark shrub. A rock. Pick one and repeat it two or three times at different sizes, smaller as it goes back toward the mountains. This does two things: gives the eye something to land on, and reinforces the depth we built two lessons ago with the far mountains sitting back.
Don't overthink where these go. I don't work by rule of thirds, I've told you that already, I just look at the paper and put the mark where it feels like it wants to be. Trust that more than you think you should.
About the paper you're using
I hope you're still working on the cheap stuff. I say this every lesson because I mean it every lesson. I dropped forty dollars on nice artist-grade paper once, early on, before I could paint anything worth putting on it. I remember standing in the store telling myself this purchase was going to make me better, like the paper does the work. It sat in a drawer for months because I was too scared to mess it up. Meanwhile I was still bad at basic washes on the cheap stuff I already owned.
Ruin the cheap paper. That's what it's for. Dry-brush technique especially — you're going to overdo it a few times before your hand learns how dry "almost dry" actually means. Better to learn that on a two-dollar pad than on something you're precious about.
One practical note: dry-brushing works differently depending on how dry your paper already is underneath. If your base wash is still even slightly damp, the dry-brush marks will bleed and soften instead of staying scratchy. Out here that's usually not a problem, our air dries washes fast, but if you're working in a humid month or painted your base wash five minutes ago, touch the paper with a clean knuckle first. If it feels cool, it's still wet. Wait.
Before next time
Practice the dry-brush drag on a scrap piece first, a dozen times, until you can feel when the brush is dry enough. Then do it once for real on your landscape and stop. You'll want to keep going. Don't.