How to Install Edging on a Slope

Written & researched by Elena Marsh Gardening & Landscaping Editor

Updated October 2026

On a slope, flexible edging should follow the grade in one continuous flowing line, while rigid modular edging must be stepped in even 2 to 4 inch drops — and in both cases you trench deeper (4 to 6 inches buried), stake roughly twice as often (every 12 to 18 inches, with 10 to 12 inch spikes), and overlap every joint with the uphill piece on the outside. Then plan where water gets out, because an edge running across a slope is a small dam. Expect a slope install to take about half again as long as the same run on flat ground.

Step 1: flowing or stepped?

A useful rule of thumb: under roughly a 10 percent grade, almost any edging can simply follow the slope. Between 10 and 25 percent, flexible edging follows and rigid units step. Above 25 percent you are really building a small terrace, and block edging doing retaining work needs proper base and drainage — at real retaining heights that becomes engineered work, covered in retaining wall cost per linear foot.

Tools and materials

• Edging plus about 10 percent extra for cuts and overlaps
• Long steel spikes, 10 to 12 inches, roughly twice as many as the manufacturer estimate
• A half-moon edger or a flat spade for the trench
• A mason line and stakes, plus a line level or a 4 foot level
• A rubber mallet, and a hand tamper for backfill
• Paver base or gravel, if you are stepping rigid units
• Gloves, eye protection, and knee pads

Installing flexible edging that follows the grade

1. Mark the line first. Lay a garden hose or spray-mark the curve and look at it from the house and from the street. On a slope, a line that looks correct standing next to it can look wrong from a distance, and it is much cheaper to fix now.
2. Warm the edging. Lay plastic coil edging out in the sun for 30 to 60 minutes so it relaxes and stops fighting you. Cold coil edging is nearly impossible to persuade into a smooth line.
3. Trench 4 to 6 inches deep, deeper than you would on the flat. Keep the trench a consistent depth relative to the finished grade so the exposed height stays even, rather than a consistent depth relative to a level line.
4. Cut a clean vertical uphill face. The edging should bear against undisturbed soil on the uphill side. That soil face is doing much of the work of holding it.
5. Set the edging with only about an inch proud of the finished grade. More than that and a mower catches it, water undercuts it, and it becomes a trip hazard.
6. Stake every 12 to 18 inches, with extra stakes at the top of the run, the bottom of the run, and every joint. Drive stakes at a slight angle leaning into the uphill side so they resist the downhill pull rather than pivoting with it.
7. Overlap joints with the uphill section outside the downhill one, by 4 to 6 inches, and put a stake through the overlap. Butted joints on a slope pull apart within a season.
8. Backfill both sides in layers, firming each one. Loose backfill on the uphill side washes out and leaves a channel that undermines the whole run.
9. Check the line from a distance before you finish the last backfill, while adjustment is still cheap.

Stepping rigid edging

1. Measure the total fall. Run a mason line from the top of the run to the bottom, level it with a line level, and measure down to the ground at the bottom. That vertical distance is your total fall.
2. Divide it into equal steps. Total fall divided by your chosen step height — typically 2 to 4 inches, or one unit height for block edging — gives the number of steps. Even steps read as intentional; uneven ones read as a mistake.
3. Mark each step position along the run with stakes so the spacing between steps is also even.
4. Excavate each level section flat and compact 2 to 3 inches of paver base in the trench. This base is what stops individual units settling and going crooked, and skipping it is the single most common reason a stepped edge looks bad in two years.
5. Set the first unit at the bottom and work uphill, checking each one for level across its own length.
6. At each step, let the uphill unit overlap or bear on the downhill one rather than leaving a vertical open joint, so soil cannot wash through the gap.
7. Backfill behind each run and firm it, and consider a strip of gravel behind block edging on steeper sections to let water drain rather than build pressure.

Plan where the water goes

This is the part people leave out and then regret. Any edge running across a slope intercepts runoff. If you give it nowhere to go, water either ponds behind the edging and saturates the bed, or it scours around one end and cuts a channel.

• Identify the low point of the run before you install anything.
• Leave a deliberate outlet there — a short gap, a section set an inch lower, or a small gravel-filled overflow.
• On long runs across a grade, put an outlet every 20 to 30 feet rather than one at the end.
• Direct the outflow somewhere it can soak away or run to an existing drain, never toward a foundation, a neighbor or a path.
• If the slope already sheds a lot of water, edging is not the fix — see yard drainage solutions and how deep a French drain should be.

Mistakes on slopes specifically

• Standard stake spacing. Flat-ground spacing on a grade lets the edge bow downhill within a season.
• Short stakes. A 6 inch spike in loose slope soil has very little holding power. Go 10 to 12 inches.
• Butted joints. They separate. Overlap, uphill piece outside.
• Trenching too shallow. Runoff scours the base and the edging lifts.
• Uneven steps. Two-inch steps then a five-inch step looks like an error. Divide the fall evenly.
• No base under rigid units. They settle unevenly and the line goes wavy.
• Damming the slope with no outlet. Ponding, saturated beds, and eventually a washout around one end.
• Edging left too proud. On a slope it catches mowers and feet even more readily than on the flat.

Aftercare

Check the run after the first heavy rain and again after the first winter. Frost heave lifts stakes, and a spike that has risen an inch is easy to tap back now and a rebuild later. Refill any scour behind the uphill face promptly. If you are also laying fabric on the same slope, it wants tighter staple spacing and cross-slope runs with the upper sheet lapped over the lower — see securing landscape fabric. For the flat-ground fundamentals this page builds on, see how to install landscape edging, and for choosing between materials, steel vs plastic edging and our landscape edging picks, where owner feedback consistently favors steel on any real grade.

Safety and site checks

Call 811 before you dig — free utility locating is required in most of the US, and a trench for edging is exactly deep enough to find an irrigation line, low-voltage cable or shallow service. Wear eye protection when driving spikes, especially into stony ground where they deflect. Watch footing on wet slopes and work across the grade rather than up and down it. If the slope is steep enough that soil is actively moving, or if the edging would be holding back more than about a foot of soil, stop treating it as edging: that is retaining wall work, it has drainage and structural requirements, and above common local thresholds — often 3 or 4 feet of exposed height — it needs a permit and an engineered design. Those thresholds are jurisdiction-specific, so check with your building department before you build anything that retains soil.

We never buy, test or physically handle the products we rank. Recommendations come from aggregated owner reviews, star ratings, review volume and expert consensus — see how we rank.

More from this hub: Landscaping & Hardscaping · Installing landscape edging · Steel vs plastic edging · Yard drainage solutions · Best landscape edging · How we rank