How to lay concrete edging for garden beds

🧱 Concrete Garden Bed Edging Trade Guide

What is concrete garden edging and why is it used in Australian landscaping?

Concrete edging is a durable, low-maintenance way to create clean lines around garden beds, paths and lawns. For Australian homeowners, it’s a practical weekend project that improves kerb appeal, helps contain mulch and soil, and outlasts plastic or timber edging in most conditions.

This guide covers how to set out, form, pour and finish concrete garden edging using DIY-friendly methods. For decorative, reinforced or structurally retaining edging, follow relevant local council requirements and ensure any significant structural work complies with AS 3600 Concrete Structures.

What skill level is required for laying concrete garden edging in Australia?

Intermediate — Estimated time: 1–2 days plus curing time

What essential tools are required for concrete garden edging projects?

What materials are needed for concrete garden edging, including mix ratios?

Safety Requirements

Step-by-Step Guide

Step 1: Plan the edging layout

Mark the garden bed shape using a hose, string line, marking paint or sand. Keep curves smooth and avoid sharp bends that are difficult to form and finish.

For most garden edging, a practical finished size is around 75 mm–100 mm wide above ground and 100 mm–150 mm deep overall. If you want a stronger edge that resists mower contact and minor knocks, aim for at least 100 mm wide.

Think about the finished height in relation to lawn, mulch and paths. A raised profile of 25 mm–50 mm above surrounding ground is common for neat definition without creating a trip hazard.

Step 2: Excavate the trench

Dig a trench along the marked line to suit the edging size. A common trench size is 150 mm–200 mm wide and 100 mm–150 mm deep, depending on your finished profile and soil conditions.

Remove loose soil, roots and organic material. If the ground is soft, wet or reactive, add and compact about 50 mm of crushed rock or road base to improve bearing and reduce movement.

Try to keep the trench base reasonably level and consistent. This makes the formwork easier to set and helps maintain an even concrete depth.

Step 3: Install and brace the formwork

Set timber boards for straight runs and flexible boards for curves. Position the forms to match the desired finished width and profile.

Drive stakes on the outside of the forms at roughly 600 mm–1000 mm centres, closer on curves. Fix the form boards securely so they won’t move when the concrete is placed.

Use a spirit level and straightedge to keep the top of the forms consistent. If you want the edging to shed water, create a slight fall of about 10 mm over a few metres rather than leaving water to pond.

For simple mower-friendly edging, you can form a slight rounded top edge. This reduces chipping and looks more professional.

Step 4: Add reinforcement if needed

For basic narrow garden edging, reinforcement is often optional. However, if the edging is wider than 100 mm, crosses tree-root zones, borders driveways, or may be exposed to movement, install galvanised trench mesh or light reinforcing.

Keep reinforcement supported so it sits roughly in the middle of the concrete depth, not buried on the ground. Small bar chairs or packed concrete dobies can help.

Reinforcement improves crack control, but it does not replace good base preparation, correct water content or proper curing.

Step 5: Mix the concrete

Mix your concrete to a workable but not sloppy consistency. For general-purpose site-mixed concrete, use 1:2:3 cement:sand:aggregate.

Only add enough water to achieve workability. Too much water weakens the concrete, increases shrinkage and leads to cracking or dusty surfaces.

If using bagged concrete, follow the manufacturer’s water recommendations closely. Mix thoroughly until colour and texture are uniform.

For larger jobs, hiring a small concrete mixer is usually more economical and much faster than hand mixing. For a short edging run, a mixing tub may be enough.

Step 6: Place the concrete

Shovel the concrete into the formwork and work it into all corners. Place it evenly along the run to avoid overloading sections of the form.

Use a trowel or a small tamping action to remove air pockets. If you have reinforcement, make sure it stays centred and covered.

Slightly overfill the forms, then use a screed board or straightedge to strike off the surface level with the form tops. Work in manageable sections so the mix doesn’t start setting before finishing.

Step 7: Shape and finish the edging

After screeding, let the concrete firm up slightly until bleed water disappears. Then smooth the surface with a steel trowel or float.

Run an edging tool along exposed arrises to create a rounded edge. This improves durability and reduces spalling. For a more natural or slip-resistant finish, use a light broom texture instead of a polished trowel finish.

If you want a decorative garden look, you can slightly dome the top profile so water sheds off both sides. Keep the finish consistent along the full length.

Step 8: Remove forms and tidy the edges

Once the concrete has gained enough strength to hold its shape, carefully remove the forms. Timing will depend on weather, mix and site conditions, but next-day removal is common.

Backfill both sides gently with soil or mulch, taking care not to chip fresh edges. Clean up any excess concrete before it hardens on tools, paving or turf.

Minor voids can sometimes be patched early, but a clean placement and proper compaction are the best way to avoid them.

Step 9: Cure the concrete properly

Curing is essential for strength and durability. Keep the concrete moist for at least 5–7 days where possible, especially in hot, windy or dry Australian conditions.

Cover with plastic sheeting or lightly mist the surface regularly. Do not let the edging dry out too quickly, as rapid moisture loss causes shrinkage cracking and weakens the surface.

Avoid impact, heavy watering, wheelbarrow traffic or lawn equipment against the edging during the early curing period.

Step 10: Reinstate the garden bed and lawn

Once the concrete has cured sufficiently, top up soil or mulch behind the edging and trim the lawn side neatly. This is where the finished line really starts to stand out.

Check that the edging height works for mowing and drainage. A well-set edge should make garden maintenance easier and reduce migration of mulch and soil into lawn areas.

Common Mistakes to Avoid

Pro Tips

Recommended Tools