Rock vs Mulch in Iowa Landscapes: Pros, Cons & When to Use Each
If you live in Iowa, you know the drill. One minute you’re scraping ice off your windshield, and the next, you’re sweating through your shirt trying to get the lawnmower started. Our weather is, shall we say, spirited. And just like your wardrobe needs to handle everything from blizzards to heatwaves, your landscape does too.
This brings us to the question we get asked constantly here at Larkin Landscape: "Should I use rock or mulch?"
It sounds simple, right? But we’ve seen this debate divide households faster than a Hawkeyes vs. Cyclones game. On one side, you have the “Mulch Purists” who love that fresh, earthy smell of spring. On the other, the “Rock Loyalists” who just want to lay it down once and never touch it again.
The honest truth? There is no single “best” answer, but there is a best answer for you. Whether you’re in Waukee, West Des Moines, or right here in our backyard, the right choice depends on your soil, your shade, and how much time you actually want to spend pulling weeds on a Saturday morning.
Let’s dig into the nitty-gritty of rock vs mulch in Iowa, strip away the sales talk, and look at what actually works in our soil.
The Case for Mulch: The Unsung Hero of Plant Health
Let’s start with the classic. When we talk about mulch in Central Iowa, we aren’t talking about that cheap stuff that fades to gray by July. We’re usually talking about high-quality shredded hardwood or cedar mulch.
There is a reason seasoned gardeners usually gravitate toward mulch. It’s not just about looks, it’s about life support.
1. It’s a Blanket for Your Roots: Iowa summers get hot. We’re talking about that heavy, humid heat that makes the air feel like soup. Shallow-rooted plants (like your hydrangeas or hostas) struggle when the sun bakes the soil. Mulch acts like a thermos. It keeps the soil cool in July and insulates it against that first hard frost in October.
2. The “Feed Me” Factor: This is the human part of nature. Mulch is organic. As it breaks down, it turns into compost. It’s literally feeding your plants while it sits there. If you have heavy clay soil (which, let’s be honest, most of us in Iowa do), decomposing mulch helps loosen that clay over time, making it easier for roots to breathe.
3. The Aesthetic: There is nothing quite like the contrast of deep brown mulch against bright green boxwoods. It pops. It looks finished. It smells like a forest. For curb appeal, a fresh layer of mulch is the cheapest facelift you can give your house.
The Downside? The “Re-Do”: Here is the reality check. Mulch disappears. It decomposes. That means you are signing up for a yearly or bi-yearly chore. You have to top it off. Also, if we get one of those nasty Midwest wind storms, lighter mulch can end up in your neighbor's yard.

The Case for Rock: The “One and Done” Warrior
Now, let’s talk about the heavy hitter: River rock landscaping.
If you drive around the newer developments in Urbandale or Grimes, you’ll see a lot of rock. And for good reason. It’s the closest thing to “permanent” you can get in landscaping.
1. Durability is King: Rock doesn't rot. It doesn’t fade much. It doesn’t turn into dirt. You pay for it once, you install it, and ten years later, it’s arguably still there. For homeowners who travel a lot or just hate yard work, this is the golden ticket.
2. Drainage Dreams: If you have a spot in your yard where water rushes through during a storm, mulch is going to float away. We’ve seen it happen a hundred times. River rock, especially the larger 2 inch stuff we tend to use, stays put. It allows water to drain through quickly without washing out.
3. No More “Mulch Mold”: In shady, damp corners of the yard, mulch can sometimes get slimy or grow that weird dog vomit fungus (yes, that’s the real name). Rock dries out faster and doesn’t host mold.
The Downside? The Heat and the Cost: Rocks get hot. Really hot. On a 90 degree day, a bed of rocks can reflect heat back onto your plants, baking them from the bottom up. You have to be careful which plants you pair with rock. Also, let’s talk budget, rock is going to cost you 3 to 4 times more upfront than mulch. It pays for itself over time, but that initial check is larger.
The Elephant in the Room: Weed Control
Here is the biggest myth in the industry: “If I put down rock, I’ll never have weeds again.”
We wish we could tell you that was true. We really do. But weeds are survivors.
With Mulch: Weed control comes from depth. You need a solid 3 to 4 inches of mulch to block the sunlight so weed seeds can't germinate. If you skimp and only do an inch, you’re going to have a weed garden. The nice thing is, when weeds do pop up in mulch, they are usually easy to pull because the soil underneath is soft.
With Rock: We always install a heavy duty landscape fabric under rock. This stops weeds from growing up from the soil. However, it doesn't stop weed seeds from blowing in on top of the rocks. Over time, dust and dirt settle in the crevices of the stones. Weeds will sprout in that dust.
Pro Tip: To keep river rock landscaping looking clean, you have to clean it. We recommend taking a leaf blower to your rock beds a few times a year to blow out the dust and leaves before they turn into soil for weeds.
So, when it comes to weed control, rock is better structurally, but neither option is magic. You still have to keep an eye on things.
The Iowa Factor: Weathering the Storms
Living in the Midwest adds a layer of complexity to the rock vs mulch Iowa debate.
The Freeze-Thaw Cycle: Our ground heaves in the winter. Rock is heavy and usually stays in place, but if you don’t have good edging (like steel or concrete pavers), those rocks will migrate into your lawn over winter. There is nothing worse than hitting a piece of river rock with your lawnmower. Clang!
The Wind: If you live on an open lot with no windbreak, lightweight mulch can be a nightmare. In those specific high-wind zones, we almost always recommend rock or a heavier, double-shredded hardwood mulch that knits together like a mat.
When to Use Which: The Larkin Landscape Cheat Sheet
Still torn? Here is how we break it down when we are designing a property for a client.
Use Rock If:
- You have drainage issues: Swales, downspout areas, or steep slopes where rain washes out soil.
- It’s a foundation bed: Many people like a clean strip of rock right up against the house foundation. It keeps moisture and bugs away from the siding better than mulch.
- You hate maintenance: If you want to set it and forget it, rock is your friend.
- You have a pool: Mulch in a pool filter is a disaster. Rock stays on the ground.
- Use Mulch If:
- You love plants: If you want a lush, cottage-garden look with lots of perennials, annuals, and shrubs, mulch is biologically better for them.
- You have trees: Trees love the “forest floor” environment mulch creates. Rock can suffocate tree roots if piled too high.
- Budget is tight: You can mulch a massive area for a fraction of the price of rock.
- You like to change things up: If you decide to move a plant next year, digging through mulch is easy. Digging through rock and cutting fabric? Not so much.
Why Not Both? The Hybrid Approach
Who says you have to pick a side? Some of the best landscapes we’ve done in Central Iowa use both.
Picture this: A beautiful border of river rock around the perimeter of the house for drainage and a clean look, but then inner “island” beds filled with cedar mulch and colorful hydrangeas. Or, using rock for high traffic pathways and mulch for the delicate planting beds.
Mixing materials adds texture and visual interest. It stops the yard from looking like a “sea of brown” or a “parking lot of stone.”
The Bottom Line
At the end of the day, your landscape needs to work for your life.
If you are retired and love spending mornings tinkering in the garden, you might not mind the annual mulching ritual, in fact, you might enjoy the smell of fresh cedar as much as we do. If you’re a busy family with three kids in soccer and a dog that runs laps around the house, river rock landscaping might save you precious hours of weekend freedom.
No matter which way you lean, the secret is installation. Rock needs quality fabric and proper edging. Mulch needs proper depth, but not volcano piles around tree trunks, please, don’t do that.
Still not sure what your yard needs? That’s what we are here for. At Larkin Landscape, we’ve seen every type of Iowa yard imaginable. We can inspect your property, look at your drainage, and give you a straight answer on what will give you the most curb appeal for your buck.
Let’s get your yard looking its best, whether that involves a truckload of rock or a bed of fresh mulch.
Ready to transform your outdoor space? Contact Larkin Landscape today and let’s get digging.
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