Ideas for Edging a Rock Garden

A rock garden should blend naturally into the rest of the garden. When the garden doesn't border grass, landscape fabric and mulches provide a gradual transition into the area, but if the rock garden borders a lawn, grasses and weeds can invade if there isn't a protective barrier. Lawn grasses can spread through roots and sideways-growing shoots, called rhizomes. Over time, the grasses spread into most areas of the rock garden unless you install a barrier to stop them. Commercial plastic lawn edging and other materials, such as bricks, help keep grass out.

Landscape fabric around the edge of a rock garden prevents weeds from sprouting, and mulches keep landscape fabric in place. Mulches also provide an attractive finish and help visually blend the rock garden into the rest of the landscape.

Gravel, crushed rock, pebbles and stone chips are some inorganic mulches you can spread over landscape fabric around a rock garden, or you could use organic mulches, such as pine bark or wood chips, but these decay and you'll need to add more each season.

The best width for the edging depends on the space around the rock garden. In a large garden, a width of 2 feet or wider offers a gentle transition into the rest of the garden, but in small yards, 1 foot may be all the space that's available. A curved, asymmetrical edge gives a natural look.

If you've mulched the bare soil in the rock garden, use the same mulch as edging to provide a natural effect.

Spade

Builder's level

Landscape fabric

Mulch, such as gravel, crushed rock, stone chips, pine bark or wood chips

Remove soil from around the edge of the rock garden with a spade to create a shallow trench. Make the trench 1 inch deep if you're using an inorganic mulch or 2 inches deep if you're using an organic mulch. Remove soil to the desired width of the edging.

Check the base of the shallow trench is level with a builder's level, adding or removing soil as necessary.

Spread landscape fabric over the base of the trench. Tuck the fabric under rocks to help conceal it and hold it in place.

Spread gravel, crushed rock, stone chips, pine bark, wood chips or another mulch over the fabric.

Place commercial lawn edging next to a rock garden if that's all the space available, or next to a border of landscape fabric and mulch to create a more gradual transition. Commercial lawn edging is made of tough plastic and it's designed to prevent lawn grasses from growing out of the lawn area, above or below ground. Lawn edging comes with stakes to prevent frost from heaving it out of the soil in cold climates.

Spade

Lawn edging

Edging stakes

Timber spikes 8 to 10 inches long and 3/8 inch in diameter, so there is 1 stake or spike for every 3 to 4 feet of edging and 1 stake for each connection point

Mallet or hammer

Lawn edging connector tubes

Sharp knife

Dig a narrow trench as deep as the edging, plus 1 inch, around the edge of the rock garden with a spade.

Avoid making sharp bends and turns, which look artificial and can encourage the edging to lift out of the ground during hard frosts.

Place the lawn edging vertically in the trench so the rounded top of the edging is level with the soil surface.

Hammer one stake or spike through the base of the edging at the bottom of the trench every 3 to 4 feet.

Cut 2 to 3 inches of the rounded top from the edging on both sides with a sharp knife when connecting two pieces of edging.

Slide a connector tube over one edge, and slide in the other ball edge, overlapping the flat edging pieces below.

Hammer a stake or spike through the overlapped pieces of edging.

Bricks, pavers or stone blocks help prevent lawn grasses from growing into a rock garden, providing they're laid on a deep trench filled with crushed rock.

Spade

Builder's level

Landscape fabric

Crushed rock

Bricks, pavers or stone blocks

Rubber mallet

Dig a trench at least 8 inches deep and twice as wide as the bricks, pavers or stone blocks with a spade.

Check the base of the trench is level with a builder's level.

Spread landscape fabric over the base and sides of the trench.

Fill the trench with crushed stone to the depth of the trench minus the depth of the bricks, pavers or stone blocks. For example, if the trench is 8 inches deep and the bricks are 4 inches deep, fill the trench to a depth of 4 inches.

Place the bricks, pavers or stone block on the crushed rock along the center of trench. Check they are level with a builder's level, and use a rubber mallet to hammer level any that are out of place.

Fill in the gaps with dug out soil, or mulch if it was used on the rock garden side of the edging.