Key takeaways
- Trench to the barrier spec, not the edging height. For Bermuda, cut a slot 5–6 inches deep with a flat spade or half-moon edger. Sod cutter first if the lawn is thick.
- Leave a ½–1 inch reveal. Flush tops get bridged by stolons within one season — this is the single most common failure.
- Stake tighter than the box says. Steel every 3–4 ft, plastic every 2–3 ft. Wide spacing lets frost and soil pressure wave the edge.
- Compact backfill on both sides. Loose soil settles, the edge tilts, and gaps open at joints. Overlap or connector-clip every joint.
- Hold mulch 2–3 inches back on the grass side. Mulch against the edge is a bridge — stolons root into it and hop over.
What's inside
For most gardens, the best edging to keep grass out of flower beds is steel landscape edging in a 6-inch height, installed with roughly 5 inches below grade and a 1-inch reveal — it’s the only widely available material that’s deep, thin, and durable enough to stop Bermuda and other runner grasses for decades. But “best” depends on your grass type, budget, and whether you can dig, so here’s how the six real contenders compare.
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How deep edging has to go to stop runner grasses
Grass invades beds two ways: rhizomes (underground stems) and stolons (above-ground runners). The depth you need below grade depends on which your lawn uses — and this is the spec most edging marketing glosses over.
| Grass type | Spread method | Typical runner depth | Minimum barrier below grade |
|---|---|---|---|
| Bermuda | Rhizomes + stolons | 0–6 in (most in top 4–6 in) | 5–6 in plus a 1-in reveal |
| Zoysia | Rhizomes + stolons | 0–4 in | 4–5 in |
| St. Augustine, centipede | Stolons (mostly on surface) | Surface | 2–3 in, but reveal height is critical |
| Kentucky bluegrass | Rhizomes | 1–4 in | 3–4 in |
| Tall fescue, ryegrass | Clumping (no runners) | — | 1–2 in; almost anything works |
The second number that matters is the reveal — the edging left above soil. Stolons simply walk over a flush-installed edge. Keep ½ to 1 inch exposed, and keep mulch pulled back a few inches from the grass side, because stolons happily root through mulch.
The 6 best edging options that keep grass out of flower beds
1. Col-Met 14-gauge steel edging — best overall for aggressive grass
Col-Met’s powder-coated steel comes in 4- to 8-inch heights and 10-foot sections at about 14 gauge (0.075 in). Buy the 6- or 8-inch height, bury it 5–6 inches, and Bermuda has effectively no path under it. The thin profile disappears visually, and staking pockets are pre-punched. Expect 15–25 years from the coated finish; scratched edges are the first rust points.
2. EverEdge — best for a nearly invisible mow line
EverEdge interlocks in 39-inch (1 m) lengths at about 1.6 mm thick, in 3-, 4-, and 5-inch heights, in galvanized, powder-coated, or Cor-Ten weathering steel. The 5-inch depth handles Zoysia and bluegrass well and slows Bermuda; for serious Bermuda pressure it’s borderline — go Col-Met 8-inch instead. Its spike-in, no-trench install is genuinely fast on soft soil.
3. Permaloc ProSlide aluminum — best for curves and wet climates
Aluminum edging in 1/8-inch thickness, heights up to about 6 inches, in 8- to 16-foot sections. It will never rust, bends cleanly around beds and trees, and hits true Bermuda-stopping depth. It costs a bit more than steel and dents more easily under string trimmers, but in irrigated or coastal gardens it outlasts coated steel.
4. Master Mark Terrace Board 5-inch (HDPE) — best budget pick that’s still deep enough
Most plastic edging fails against runners, but this is the exception: a recycled-HDPE coil roughly 5 inches tall and about 1/8 inch thick in 20- or 40-foot rolls, at roughly a third of steel’s cost per foot. Trench it in at 4–5 inches with stakes every 2–3 feet and it will hold back Zoysia and moderately aggressive Bermuda. Weak points: it needs more stakes on curves, the top edge gets chewed by trimmers, and UV chalks it after 8–12 years.
5. Recycled rubber edging (EcoBorder, Rubberific) — best no-dig option, with a caveat
L-profile recycled rubber sections about 4 inches tall and 4 feet long, held by spikes. Only 1–2 inches sits below grade, so it genuinely stops surface-stolon grasses like St. Augustine — but it will not stop Bermuda unless you trench it deeper. UV-stable and trimmer-friendly; figure 8–10+ years. The right choice when digging isn’t possible and your grass creeps on the surface.
6. Soldier-course pavers on a concrete edge restraint — best permanent hardscape edge
4×8-inch pavers (Pavestone, Belgard, or similar) set upright or flat on 2–3 inches of compacted base, locked with a concrete haunch at least 4 inches wide on the grass side. The real barrier is the concrete, not the stone — total effective depth around 5–6 inches, indefinite lifespan, and a flat course doubles as a mow strip. Most labor-intensive and most expensive option here.
Head-to-head: the specs that decide it
| Edging | Max install depth | Thickness | Section/coil length | Realistic lifespan | Typical cost per lin. ft | Stops Bermuda? |
|---|---|---|---|---|---|---|
| Col-Met steel | 7–8 in | 14 ga (~0.075 in) | 10 ft | 15–25 yrs | $3–7 | Yes, at 6-in burial |
| EverEdge steel | 4–5 in | ~1.6 mm | 39 in | 20+ yrs | $4–8 | Marginal — slows it |
| Permaloc aluminum | ~6 in | 1/8 in | 8–16 ft | 25+ yrs | $3–6 | Yes, at 6-in burial |
| Terrace Board HDPE | 4–5 in | ~1/8 in | 20–40 ft coil | 8–12 yrs | $1–2 | Mostly, if trenched deep |
| Rubber no-dig | 1–2 in | ~1/2 in | 4 ft | 8–10 yrs | $3–5 | No (surface install) |
| Paver + concrete haunch | 5–6 in | ~2.4 in paver | Per piece | 25+ yrs | $5–10 | Yes |
Which edging for your situation
| Your situation | Pick | Why |
|---|---|---|
| Bermuda or kikuyu invading every spring | Col-Met 6–8 in steel | Deepest practical burial, permanent |
| Wet, irrigated, or coastal garden | Permaloc aluminum | Zero rust at cut ends and scratches |
| ~40 ft of bed on a tight budget | Terrace Board 5-in | Cheapest way to reach 4–5 in depth |
| Rental, or can’t trench | Rubber no-dig | Surface install; only for stolon grasses |
| Want the edge to disappear | EverEdge | Thinnest visible line, fast install |
| Want it done once, forever | Paver soldier course | Concrete haunch outlives everything |
Installation: the part that actually stops the grass
Depth failures cause more re-invasion than material failures. Do it once, properly:
- Trench to the barrier spec, not the edging height. For Bermuda, cut a slot 5–6 inches deep with a flat spade or half-moon edger. Sod cutter first if the lawn is thick.
- Leave a ½–1 inch reveal. Flush tops get bridged by stolons within one season — this is the single most common failure.
- Stake tighter than the box says. Steel every 3–4 ft, plastic every 2–3 ft. Wide spacing lets frost and soil pressure wave the edge.
- Compact backfill on both sides. Loose soil settles, the edge tilts, and gaps open at joints. Overlap or connector-clip every joint.
- Hold mulch 2–3 inches back on the grass side. Mulch against the edge is a bridge — stolons root into it and hop over.
What wears out first — ownership realities
- Steel: the powder coat fails where string trimmers and shovels hit it; touch up scratches or accept surface rust (cosmetic, not structural, for years).
- Plastic: stakes snap before the coil does — buy extras. The exposed top lip chalks and nicks after year 5 or so.
- Rubber: sections shift on slopes; check and re-spike each spring.
- Pavers: a thin concrete haunch cracks and lets rhizomes through — keep it at least 4 inches deep, and expect to re-set a stone or two after hard freezes.
- Everywhere: frost-heave climates punish shallow installs. Under 3 inches buried, expect to re-tamp sections every spring.
FAQ
Is 4 inches deep enough to stop Bermuda grass?
Marginally — most rhizomes run in the top 4–6 inches, so a 4-inch barrier stops many but not all. If Bermuda is established and irrigated, install at 6 inches or accept occasional pruning of escapes.
Will grass grow under edging even if it’s deep enough?
Rarely under — usually over. Stolons cross a flush or heaved edge and root in your mulch. Depth plus a 1-inch reveal plus a pulled-back mulch strip is the complete system.
Does mulch alone keep grass out of beds?
No. Mulch slows clumping grasses but stolon and rhizome grasses treat it as a growing medium. It’s a supplement to a real barrier, not a substitute.
