8 Types of Landscaping Rocks and How to Choose One

Crushed Stone

Best for: Mulch

While most types of mulch are organic and decompose over time, crushed stone is an inorganic type. It comes from stone quarries. The stone (commonly granite) passes through a crushing machine. The end result is an aggregate of small (about 1 inch) stones with an angular shape.

Although it has other uses (such as underlayment for patios), crushed stone is especially useful in mulching around certain types of plants and in creating a patch of yard where dogs will be kept. Dogs can destroy a lawn. In contrast with grass, crushed stone offers a low-maintenance option that minimizes the mess dogs make through digging, urination, and wear and tear.

As a mulch in planting beds, crushed stone works better in some instances than others. In a sunny area, stone gets hot in the summer. This heat retention may bother some annuals and perennials. Trees and shrubs are generally tough enough that they are not bothered. To be on the safe side, use crushed stone only around drought-resistant plants, and do not apply it directly up against your plants.

Crushed stone is available at stone yards and can also be ordered through major home improvement centers; you'll probably need to have it delivered (unless you own a truck). It costs more than most other types of mulch, but you recoup your expense over time because of its durability.

Black Polished Pebbles

Best for: Accents in water features

Black polished pebbles are highly ornamental and widely available at home improvement centers. A benefit here, unlike with crushed stone, is that you can buy them by the bag. This puts you in better control as a DIY'er. If you don't need many of them, this also keeps the cost down somewhat, although they are more expensive than similar natural beach pebbles. To create a contrast, mix white marble pebbles with your black polished pebbles.

They go by various other names, including black polished river rock and black polished beach pebbles

Black polished pebbles are quartzite stones that have been tumble-polished to give them their shine. They have a wide variety of landscaping uses other than as accents in water features, including as:

• Mulch to edge walkways, planting beds, and patios
• Filler in between plants in container gardens
• A dark element for contrast with lighter rocks in a dry creek bed

You can also buy natural beach pebbles. You might regard them as a better option because they're cheaper, although they lack the shine that people value in black polished pebbles (whose shine also makes them look darker). Moreover, the shine of the polished stones does fade over time, especially when subjected to full sun.

River Rocks

Best for: Dry creek beds

"River rocks" refers not to a geological classification but to a place of origin. Gathered from river beds, these stones have been rounded and smoothed by nature. They come in all sizes, from gravel to boulders. In fact, they look best in such a mix. You can order them online from home improvement centers.

River rocks are tailor-made for dry creek beds, where, aesthetically, the aim is to create a natural-looking landscape feature. Besides appearance, though, dry creek beds have a practical function:

If you have a hill on your land where excess water flows or collects, water may pool in areas where you don't want it to, such as near a house. You can address this drainage problem with a dry creek bed. When runoff gets bad, excess surface water is channeled down the dry creek bed to a place where it will be less problematic.

Lava Rocks

Best for: Accents in rock gardens

Like black polished pebbles, you can buy lava rocks in bags at home improvement centers at a reasonable price. While red is a popular color, they also come in black. Choose your color based on your design needs.

Lava rocks can work well in rock gardens as accents. If possible, look for a color match with your house or another landscape feature. Your color selection may even be influenced by the plant material in your rock garden. Red lava rocks look good with hen-and-chicks plants (Sempervivum tectorum) when they turn red, for example, while white flowers contrast nicely with black lava rocks. Lava rocks are also well-suited to fire pits.

Flagstone

Best for: Walkways and patios

Flagstone is sedimentary rock of various types (sandstone, slate, etc.) that has been quarried and sold in flat slabs. Its flatness and durability readily suggest its use as a paving stone upon which people walk in walkways and patios.

For informal walkways, wood chips and other materials may be fine; but, for formal walkways, it's hard to beat flagstone. With its irregular shapes, it's more interesting to look at than brick or concrete pavers. Generally, a mix of colors looks best. Alternatively, if you are trying to match or complement your house color, you can build a flagstone walkway or patio in one color.

You can buy flagstone at stone yards and through some home improvement centers. While flagstone is not expensive compared to concrete pavers, the labor involved in installing it is greater. So install yourself if you can. Building a flagstone walkway is well within the skill set of the average DIY'er.

Cobblestone

Best for: Driveway aprons

Cobblestones exude a traditional charm that makes them irresistible for some people. A quarry product, cobblestones (or "Belgian blocks") come from basalt, limestone, or, especially, granite that has been cut into a rectangular shape.

A popular use for them is in driveway aprons. This is particularly popular with people who like the look of cobblestone pavers but can't afford to build a whole cobblestone driveway. If you're doing the job yourself, you can pick up cobblestones at a stone yard.

The most durable of the pavers, the drawbacks of cobblestones are cost and roughness of surface: If you're having them installed, they cost $40 to $70 per square foot, and their exterior is just uneven enough to make snow removal difficult.

Fieldstone

Best for: Stone walls, including stone retaining walls

As with river rocks, "fieldstone" refers not to a geological classification but to the place this type of rock originally called home. Farmers plowing their fields in rocky country encountered a multitude of stones. To get them out of the way, they would pile them up somewhere away from where they'd be growing crops. As the need arose, they might harvest rocks from the pile to build a wall out of this "fieldstone."

The stone wall is one of the oldest uses of stone. Stone walls come in many styles. The most basic distinction is between mortared and mortarless walls. But a variety of rocks can also be used. Flat ones are best for mortarless walls (and also work well in stepping stone paths). If your fieldstone is rounded, mortar may be necessary to hold the pieces together. Stone retaining walls are a distinct sub-class; they have specialized requirements that, in some cases, call for professional help.

You can order fieldstone from a home improvement center or a stone yard; either way, you'll probably have to have it delivered. It's heavy, but it's not particularly expensive if you settle for the ubiquitous local fieldstone in your area.

Boulders

Best for: Terracing, accents that need to show up from a distance

While, technically, a "boulder" is any rock that measures about a foot or more in diameter, the term, in common usage, is restricted to a rock that is too heavy for a person to move unaided. Shape plays no part in the classification: A boulder can be rounded or can have flat sides. Boulders cut across many rock types, including granite, limestone, marble, and quartzite; cost will be dependent on rock type, as well as factors such as where you live.

Available at stone yards, you'll probably need to have boulders delivered to your property. If you've hired landscapers for the installation, they'll make the necessary arrangements.

In landscaping, boulders are typically thought of as rocks so massive that they show up from a distance and/or provide structure for landscape features. For example:

• Make a big impression at a driveway entrance by flanking it with either rounded boulders or flat, pillar-like boulders. Choose a color for these accents that complements your house and/or other features in your yard.
• Placed properly, boulders retain enough soil behind them to be useful in terracing a slight slope
• Incorporate a boulder in your rock garden in a way that looks natural. Don't just place it on the surface: Bury most of it (as you would find it in nature), leaving just enough exposed to suggest how much lies under the surface.
• Flat boulders are just the kind of massive slabs that are useful in constructing sturdy outdoor steps.
• A boulder can be plumbed by a stonecutter to function as the central feature in a garden fountain