Short answer
For a bed next to lawn, use an edge that goes at least about 4 inches into the soil to slow grass runners, with about 1/2 to 1 inch showing so a mower can pass. Steel or aluminum strip gives the cleanest line, plastic coil is the cheapest, and brick or stone suits cottage and formal beds. If the bed is not next to lawn, a no-dig or low decorative border that just holds mulch is enough.
What a flower bed edge has to do
Most beds sit next to lawn, so the edge first has to stop grass. Lawn grasses such as bluegrass spread by underground runners, and a shallow border sitting on the soil does little to stop them. University of Illinois Extension notes that a spade-cut edge about 4 inches deep and 4 inches wide contains bluegrass, which is a useful guide for how deep a bought edge should reach too.
The second job is holding mulch and soil in place. A lip of about 1/2 to 1 inch above the lawn side (a common rule of thumb, not a fixed standard) keeps mulch from spilling while still letting a mower wheel ride past. Beds that are not next to lawn, such as a border along a fence or a bed beside a patio, only need this second job done, and a shallow no-dig edging is often enough.
Which materials suit flower beds
| Material | Why pick it for a bed | Watch for |
|---|---|---|
| Steel strip | Thin, crisp line; holds curves; deep enough for grass | Sharp top edge; cost |
| Aluminum strip | Light, easy to curve, does not rust | Dents more easily than steel |
| Plastic coil | Cheapest; bends into any curve | Can heave in frost and look wavy |
| No-dig plastic | No trench; good where there is no lawn | Too shallow to stop grass roots |
| Brick | Classic look; reclaimed brick is cheap | Needs a sand base or it shifts |
| Natural stone | Cottage and natural gardens | Grass creeps through gaps |
| Wood | Warm, rustic; easy for straight beds | Rots in constantly damp soil |
| Rubber | Flexible, sits at the surface | Looks less natural up close |
Not sure where to start? The edging picker asks four questions and suggests a material, and materials compared covers the trade-offs in more depth.
Flower bed edging options
-
01Cleanest line
Steel or aluminum strip
Best for: lawn-side beds where you want the edge to almost disappear
- Height
- About 4 to 6 in
- Shows
- About 1/2 to 1 in
- Install
- Narrow trench, stakes
- Deep enough to slow grass runners
- Holds flowing curves
- Full guide: metal landscape edging
-
02Low cost
Plastic coil edging
Best for: long, curvy beds on a tight budget
- Height
- Often about 4 to 5 in
- Form
- Coil with stakes
- Install
- Shallow trench
- Hunker says most plastic edging is 4 inches tall
- A rounded top bead looks tidier than a flat top
- Full guide: plastic edging
-
03Classic
Brick or stone border
Best for: cottage, traditional and formal flower beds
- Base
- Sand or concrete
- Width
- 4 in or more for stone
- Install
- Trench plus base
-
04No trench
No-dig border
Best for: beds along fences, patios and walls with no lawn next to them
- Height
- Shallow lip
- Install
- Spikes, no digging
- Stops grass
- Not well
- Fast to put in and easy to move
- Holds mulch at the surface
- Full guide: no-dig edging
What height to use
Think of height in two parts: what is buried and what shows.
- Buried part: enough to stop grass runners and keep the edge from lifting. For strip edging this is usually 3 to 5 inches. Gertens suggests leaving metal edging about 3/4 to 1 inch above grade.
- Visible part next to lawn: low, so a mower wheel can ride over or beside it. About 1/2 to 1 inch is a common target.
- Visible part on the bed side: a little more if you keep a deep mulch layer, so the mulch sits below the lip.
Every material has its own depth. The table and drawing are in how deep to install landscape edging.
Raised bed edging
A raised flower bed needs an edge that holds back the full depth of soil, not a lawn border. The usual choices:
- Timbers or treated boards. Illinois Extension describes timbers and treated 2x4s held with rebar, with corners toenailed, and warns against old creosote railroad ties near plants (Illinois Extension). Hunker notes treated wood can last a decade or more but is not for constantly damp spots (Hunker).
- Weathering steel. Tall Corten edging makes a slim raised edge with a rust finish. Keep it back from pale paving while it weathers.
- Stacked stone or block. Good for low raised beds of a course or two. Taller stacked walls are a retaining wall job, not edging.
Curves, corners and mulch
Lay the bed shape out with a garden hose first and live with it for a day. Wide, smooth curves are easier to mow around and easier for strip edging to follow than tight wiggles. Plastic, steel, aluminum and rubber all bend; brick and timber need short pieces or angled joints. Keep the finished mulch a little lower than the edge top so it does not wash over in rain.
For more looks, browse landscape edging ideas. If the bed borders a path, see garden path edging; if it holds stone or rock instead of mulch, see edging for gravel and mulch.
Putting it in
What you need
Step by step instructions for every type are in how to install landscape edging, and prices are in landscape edging cost.
Questions people ask
What is the best edging for flower beds?
For a bed next to lawn, steel or aluminum strip edging gives the thinnest, longest-lasting line and goes deep enough to slow grass. Plastic coil is cheaper and easy to bend. Brick and stone look best in classic or cottage gardens but let grass creep through the joints unless they sit on a base. For a bed that only needs to hold mulch, a low no-dig border is fine.
How tall should flower bed edging be?
Most bed edging is about 4 to 6 inches tall overall, with most of it buried. A common aim is to leave about 1/2 to 1 inch above the soil next to lawn so mowers can roll past, and a little more on the bed side if you top up mulch. Raised beds need an edge as tall as the soil you are holding back.
Do I need edging around a flower bed at all?
No. A spade-cut (trench) edge works well and costs nothing. University of Illinois Extension describes a cut about 4 inches deep and 4 inches wide that contains bluegrass and needs touching up once or twice a year. Edging saves that upkeep and holds mulch better.
What is the cheapest flower bed edging?
A spade-cut edge is free. Of the bought materials, plastic edging is usually cheapest, about $1 to $3.50 per linear foot in material according to LawnStarter. Reclaimed bricks or stones from your own yard can also cost little or nothing.
How do I stop mulch washing out of a bed?
Keep the mulch surface a little below the top of the edge, so the edge acts as a lip. On slopes, use a taller rigid edge such as steel, timber or stacked stone, and keep mulch depth even rather than heaped against the edge.
Sources
Last reviewed October 12, 2026. Products, sizes and listings change; check the product details before you buy, call 811 before you dig, and follow the maker’s instructions.