Pressure Treated Lumber for Landscape Edging: A Step-by-Step Guide

By Caleb Morgan

Updated November 2026

Pressure treated lumber for landscape edging gives you a low-profile, easy-to-shape border that holds back mulch and turf without a lot of specialty hardware. In this guide, you will learn how to pick the right boards, cut and stake them, set them to the correct height, and finish the job so the edge stays straight for years. You will also see the mistakes that cause early rot and heaving, and how to avoid them.

Why Pressure Treated Lumber Works for Edging

Pressure treated wood is softwood, usually pine or fir, that has been impregnated with preservatives to resist rot, fungi, and insects. For edging, that resistance matters because the boards sit in damp soil and get hit by mower wheels, string trimmer splash, and constant moisture. Untreated pine can start to soften within a couple of seasons at ground contact. Treated boards, when rated for ground contact, can last considerably longer.

Shopping for one? See our guide: 6 Best Easyflex No Dig Landscape Edging Kit Options for Clean Lines (2026).

The trade-off is that the preservatives are chemicals, and some older treatments used copper arsenate or chromated copper arsenate, which are no longer used for residential lumber. Modern residential treatments, such as copper-based formulations, are generally considered suitable for ground contact, but you should still follow the manufacturer’s labeling and local rules. If you plan to grow edibles right against the wood, or you are concerned about leaching, a material like steel, aluminum, or stone may suit you better. For comparisons of other options, see What Are the Best Options for Landscape Edging? 7 Choices Compared.

Choosing the Right Lumber

Lumber for edging is not the same as lumber for a deck or a fence post. Look for the ground-contact rating on the tag or stamp. The label will typically say something like “Ground Contact” or “UC4A,” which indicates the retention level suited to in-soil use. For a lawn edge that sits partly in the ground and partly exposed, a ground-contact rating is the right choice. Above-ground-only boards will rot faster where they touch soil.

Board Dimensions That Work

Most edging projects use 2×4 or 2×6 boards, and some use 1×6 or 1×8 boards for a lower profile. A common approach is to bury about one-third of the board’s height and leave the rest above grade. For a 2×6 (actual dimension 1.5 x 5.5 inches), that means setting roughly 2 inches into the soil and leaving about 3.5 inches exposed. For a lower border of 2 to 3 inches above grade, a 2×4 or 1×6 is often enough.

Lengths and Joints

Pressure treated boards are commonly sold in 8-, 10-, and 12-foot lengths. Plan your run so you use the fewest joints possible, and stagger any joints so they do not line up. Where two boards meet, cut them square and butt them tightly, then secure the joint with a stake on each side.

Tools and Materials Checklist

Gather everything before you start digging. It saves time and keeps the trench consistent.

• Pressure treated boards rated for ground contact
• Wood stakes, typically 2×2 or 1×2 ground-contact lumber, about 12 to 18 inches long
• Exterior-rated deck screws or galvanized nails, 2.5 to 3 inches long
• Circular saw or miter saw for square cuts
• Spade or flat shovel for the trench
• Mason’s string and line level
• Hand tamper or the back of a shovel for compacting soil
• Drill with a driver bit and a pilot drill bit
• Landscape fabric, optional, to slow weeds at the edge
• Eye and ear protection, plus a dust mask when cutting treated wood

Step-by-Step Installation

Step 1: Lay Out the Line

Mark the edge with a garden hose or spray paint so you can see the curve or straight run. Pull a mason’s string tight alongside the line for straight runs. Measure the distance from the string to the edge of the bed to confirm the line is consistent along its length.

Step 2: Dig the Trench

Dig a trench just deep enough to bury the board to the depth you planned, typically 1.5 to 2.5 inches for a 2×6. Keep the trench bottom level with the back of your spade so the board sits evenly. Remove sod, roots, and rocks that would create gaps. For curves, dig with a slightly wider bed so the board can be bent gently.

Step 3: Cut and Dry-Fit the Boards

Cut each board to length with a square end. Set all boards in the trench without fastening them and check the height along the full run. Adjust the depth in low spots by adding or removing soil, not by forcing the board. A consistent top line is the main thing that makes edging look finished.

Step 4: Stake and Fasten

Drive a stake on the inside of the bed, meaning the side toward your plants or mulch, every 18 to 24 inches. Set each stake so its top sits slightly below the board’s top edge. Pre-drill the board and stake, then fasten with two screws per stake. Stakes on the inside keep the mower and trimmer from knocking the board over.

Step 5: Backfill and Tamp

Backfill the outside of the trench with soil and tamp it firmly, working in layers. Loose soil lets the board wobble, and wobble leads to gaps and weeds. Check the top line again after tamping.

Step 6: Finish the Edge

If you want fewer weeds in the seam, lay landscape fabric along the inside of the board before adding mulch, and trim it flush. Backfill the bed and rake the mulch or soil to the top of the board so the edge reads as a clean line.

Spacing, Height, and Layout Reference

The table below gives typical starting points. Adjust for your soil, slope, and mowing habits.

Common Mistakes to Avoid

• Using boards without a ground-contact rating. Above-ground lumber rots quickly where it meets soil.
• Skipping stakes. Without them, boards heave with frost and shift with mower impact.
• Cutting into the top edge. Damaged cuts collect water and split faster. Cut square and sand rough ends lightly.
• Setting the board too high. A board sitting well above grade gets knocked by equipment and looks unfinished.
• Ignoring drainage. A solid wall can trap water on the uphill side. Leave small gaps at low points or use a gravel base.
• Trimming too close with a string trimmer. String trimmers chew wood and speed rot. Keep the trimmer head angled away from the board.

Tips for Longer-Lasting Results

• Allow cut ends to dry before painting or sealing, and apply a sealer labeled safe for treated wood to exposed cuts.
• Use hot-dipped galvanized or stainless fasteners, since standard steel fasteners corrode in treated lumber.
• Check the edge each spring for loose stakes and re-tamp as needed.
• Keep mulch a few inches away from the board where possible to reduce moisture exposure.
• Replace boards that show soft spots by pushing a screwdriver into the wood. Soft wood means rot has set in.

Recommended gear

A few supplies make the job cleaner and the results longer-lasting. For fasteners, look at exterior-rated screws designed for treated lumber, since they resist corrosion from preservative chemicals. View on Amazon

A mason’s string and line level help you keep the top edge level across long runs, which is the main visual goal of any edging project. View on Amazon

A hand tamper packs backfill soil around the board so it does not wobble over time. View on Amazon

A sealer labeled for use on treated wood helps protect cut ends and exposed faces from moisture. View on Amazon

FAQ

Is pressure treated lumber safe for landscape edging?

Modern residential pressure treated lumber is generally considered suitable for ground contact when labeled for it. Avoid burning it, follow the label on handling, and wear gloves and a dust mask when cutting. If you grow edibles very close to the wood, consider a different material to limit any chemical exposure.

How long does pressure treated edging last?

Lifespan depends on the wood’s retention rating, soil moisture, drainage, and how well the boards are installed. Many installations last well over a decade, but the exact life varies widely by climate and conditions.

Should I use 2×4 or 2×6 boards?

A 2×4 suits a low, subtle border, while a 2×6 gives more stability and a stronger visual line. Choose based on how tall you want the edge to stand and how much soil you need to bury for support.

Do I need stakes for every board?

Stakes are strongly recommended, usually every 18 to 24 inches on the inside of the bed. They keep the boards from heaving and from being pushed out by mowers or mulch pressure.

Can I paint or stain pressure treated edging?

Yes, once the wood has dried for several weeks. Use a finish labeled for treated lumber. Stains can change the look, and some finishes wear faster on ground-level boards, so test on a scrap piece first.

What is the best way to stop weeds along the edge?

Lay landscape fabric along the inside of the board, trim it flush, and cover with mulch. Keep the trench compact and free of root debris so the fabric sits flat.

Can I curve pressure treated boards?

Gentle curves are possible with standard dimensional lumber, especially thinner boards like 1×6. Tight curves may require kerf cuts on the back side or a different material. Dry-fit before fastening.

When should I consult a professional?

If your edge runs along a retaining wall, a slope with drainage concerns, or a structure near a foundation, consult a landscape contractor or structural professional before you build.

Conclusion

Pressure treated lumber gives you a durable, affordable-looking edge when you choose ground-contact boards, set the depth correctly, and stake each run securely. Take time with the layout and tamping, since those steps decide whether the line stays straight. Follow the checklist and avoid the common mistakes, and your border should hold its shape for many seasons.

Related reading

• Wood Landscape Timber Edging: A Step-by-Step Install Guide
• Vigoro No-Dig Landscape Edging Kit: A Step-by-Step Install Guide

About Caleb Morgan

Caleb Morgan is part of our editorial team and reviews and edits our lawn edging & trimming guides, checking product details against manufacturer specifications and owner feedback.