Stone lawn edging gives a garden a crisp, natural border that can last for many years. Unlike lighter plastic or metal strips, stone relies on its own weight and thickness to stay in place and block grass from creeping into beds. Getting the size right and setting the stones on a proper base makes the difference between an edge that shifts with frost and one that holds its line season after season. For comparisons, see brick edging, metal edging, the lawn edging materials guide and the lawn edging types section.
Why stone size matters
Rhonda Ferree, Horticulture Educator with University of Illinois Extension, points out that stone used for edging should be at least 3 inches thick and at least 4 inches wide to stop the grass. A thinner or narrower piece may allow grass rhizomes to travel underneath, undoing the separation you are trying to create.
Choosing stones that meet these minimums gives the edge enough mass to resist minor bumps from foot traffic and lawn equipment. The Illinois Extension notes that a sand or concrete base, containing reinforcing rods, provides added durability and strength. Without a solid base, even heavy stones can settle unevenly over time, especially in areas with freeze-thaw cycles.
Planning your stone edging line
Before you break ground, decide on the shape. The Royal Horticultural Society (RHS) advises that broad, sweeping curves are easier to maintain than intricate shapes. Straight edges create a formal look, while curved edges soften the garden. To mark a straight line, the RHS suggests tying a string between two canes or pegs and pulling it taut at ground level. For curved edges, use something flexible like a garden hose, rope or string. View the marked-out edge from several angles, including from an upstairs window if possible, and adjust until you are happy with the position.
Once the line is set, you can cut the edge. The RHS recommends using a half-moon edging tool or a flat-backed spade. If you use a spade, mark a depth of 7.5 cm (3 in) on the blade with tape and insert it to that depth. Work along the line, taking small steps and overlapping the cuts slightly to create a continuous slit. Then go back and lift narrow strips of grass by hand, or slide the spade underneath larger pieces. The unwanted turf can be composted.
This cut defines the lawn side of the trench where the stones will sit. The RHS also notes that a well-defined lawn edge with a decent drop down to the border helps keep mulching material in place. Aim for a drop of about 7.5 cm (3 in) from the lawn surface to the bed. That drop makes it harder for grass stolons to bridge the gap and simplifies trimming later.
Preparing the trench and base
Any digging deeper than a few inches calls for a call to 811. The national before-you-dig service states that you should contact 811 or your state 811 center’s website a few business days before you begin any digging, including projects like installing landscape edging. You will need to provide the address, county, nearest cross street, the type of project, and the exact area where you plan to dig. After you contact 811, wait the required time for utilities to mark their buried lines, then dig carefully around any marks.
With utilities marked, excavate a trench along the cut line. The trench needs to be wide enough for the stones and deep enough to hold the base material plus the stone so the top of the stone sits at the desired height. The Illinois Extension states that a sand or concrete base provides added durability. For a sand base, spread a layer of coarse sand and tamp it level. For a concrete base, mix and pour a footing, and consider adding reinforcing rods as the Extension suggests for extra strength. Let the concrete cure before placing stones.
Setting the stones
Place each stone into the prepared base, butting them tightly together. Check that the tops are even and that the face on the lawn side creates a continuous vertical plane. A rubber mallet helps tap stones into the sand or fresh concrete without chipping them. Step back frequently to sight down the line and correct any wobbles.
Once the stones are set, backfill the bed side with soil and the lawn side with a little topsoil or sand to close any gaps. The Illinois Extension’s minimum width of 4 inches means the stone itself acts as a barrier; grass has to travel a longer distance to reach the bed, which reduces encroachment. If you are using irregular flagstone, choose pieces that still meet the thickness and width guidelines and fit them as closely as possible.
Maintaining stone lawn edges
Stone edges need regular attention to stay crisp. The RHS advises redefining the edge with a half-moon edging tool annually: insert the blade downwards along the lawn side to cut away slivers of grass that have crept over the stone. This annual reset makes routine trimming easier.
For routine upkeep, the RHS recommends using edging shears after each time you mow the lawn. When grass is growing strongly, this may be as often as once a week. Hold the shears upright with the blades beside the lawn edge, keep the handle attached to the lower blade steady, and move the upper handle to cut overhanging grass. Take small sideways steps and slightly overlap each cut to avoid leaving tufts. Rake up the clippings and compost them, or flick them into the border with a hoe if only short sections were cut.
Keeping the shears sharp gives a clean cut and reduces effort. The RHS also points out that edging shears with long or telescopic handles are useful for tall gardeners. If you use a string trimmer for edging, follow the manufacturer’s safety instructions and hold the tool so the line strikes the soil at the edge of the stone, not the stone face, to avoid chipping.
Checklist for stone lawn edging
- Contact 811 a few business days before digging and wait for utilities to mark lines.
- Mark the edge shape with string (straight) or a hose (curved) and view from multiple angles.
- Cut the lawn edge with a half-moon edger or spade, creating a clean slit and a drop of about 3 inches.
- Remove grass strips and dig a trench wide and deep enough for the base and stones.
- Prepare a sand or concrete base; tamp sand level or let concrete cure.
- Set stones at least 3 inches thick and 4 inches wide, butted tightly, and tap them level.
- Backfill gaps and check the line is even.
- Redefine the edge annually with a half-moon tool and trim after mowing with sharp shears.
Frequently asked questions
How thick should stone lawn edging be?
According to the University of Illinois Extension, stone edging should be at least 3 inches thick. This thickness helps the stone stay put and blocks grass from pushing underneath.
Do I need a concrete base for stone edging?
The Illinois Extension says a sand or concrete base provides added durability and strength. A concrete base with reinforcing rods offers the most resistance to shifting, but a well-compacted sand base can work in many situations. The choice depends on your soil and how much movement you expect from frost.
How do I keep grass from growing between the stones?
The RHS recommends trimming edges regularly with edging shears after mowing and redefining the edge annually with a half-moon tool. A drop of about 3 inches from the lawn to the bed also discourages grass from bridging the gap. Tightly butted stones that meet the 4-inch width guideline leave less room for grass to sneak through.
For more on stone lawn edging options and installation, visit our stone edging guide.
