Installing plastic landscape edging requires marking a path, digging a 4-inch trench, setting the edging with the bottom V-lip facing the bed, staking every 3 to 4 feet, and backfilling with compacted soil to lock it in place.
A crooked lawn edge nags every time you mow. Plastic landscape edging fixes that boundary in an afternoon with basic tools, but the order and depth of each step decide whether the border stays put or heaves by midsummer. The process breaks into straightforward stages, and common DIY mistakes are easy to avoid once you know where they hide.
What You Need Before You Dig
Plastic edging arrives coiled tight and wants to spring back. The most overlooked first step is letting it relax. Skip this, and the edging fights you all the way down the trench. You will also need a flat-blade shovel or half-moon edger, a rubber mallet, landscape stakes rated for your edging height, and heavy-duty garden shears or a hacksaw. Browse our tested plastic edging picks for recommendations on products that hold up across different soil types.
Marking the Path and Digging the Trench
Lay a garden hose, rope, or stakes with string along the intended border and step back to check the curve. Once the line looks right, spray marking paint or trickle flour along the path. For the trench, dig 4 inches deep for standard residential edging — deep enough to hide the ridge below grade but shallow enough that the top sits about half an inch above the soil. If edging a bed that fights grass runners, go 5 to 6 inches deep. The lawn side of the trench should be cut nearly vertical; the bed side can slope. This orientation keeps grass roots from tunneling under the edging later.
Setting the Edging and Driving Stakes
Place the relaxed edging into the trench with the bottom V-lip facing the mulch, rocks, or bed soil — never the lawn. That lip is the anchor that stops the edging from being pushed sideways by root pressure. For products like Master Mark Classic Edging or Vigoro’s standard roll, keep the top reveal consistent at roughly half an inch above grade. Drive a landscape stake through the side wall every 3 to 4 feet, angling the stake at 45 degrees away from the lawn. On curves, ends, and any stretch longer than 12 feet, add extra stakes every 2 feet. Use a rubber mallet to seat the stake flush with the top edge — a metal hammer cracks the plastic. The Home Depot installation guide confirms this sequence and warns against leaving too much edging exposed above grade, which lets mower wheels pop the stakes loose.
Connecting Sections and Finishing the Seam
Most plastic edging rolls come with straight couplers and may offer separate corner connectors for 90-degree turns. Slide the coupler halfway into one strip, then join the next strip so the seam is tight. For corners, Master Mark recommends dedicated corner connectors rather than bending the straight coupler — forced bends create weak points that snap under frost heave or root pressure. Stagger the joint away from any stake so the coupler sits between stakes. Butt the seam firmly, tap it level with the rubber mallet, and move on.
Backfilling and Compacting
Scoop the saved trench soil back into the gap on both sides of the edging, but do not just dump it. Pack the soil firmly against the plastic with your boot or the flat back of the shovel, working in 2-foot sections so the edging does not shift. The goal is zero visible gap between soil and edging — any void invites settling that tilts the border. After backfilling, water the line gently to settle fine soil into air pockets, then tamp once more. Run the mower over the area the next week, check for exposed stake heads or leaning sections, and tap them back into place. A correct install should last several seasons with only minor tune-ups after freeze-thaw cycles.
References & Sources
- The Home Depot. “How to Install Plastic Edging.” Covers trench depth, stake spacing, orientation, and backfill procedure.
- Vigoro. “Vigoro Plastic Lawn Edging Instructions.” Specifies warming times by temperature, 4-inch trench depth, 45-degree stake angle, and V-lip orientation.
FAQs
Should the plastic edging lip face the lawn or the garden bed?
The bottom V-lip must face the flower bed, mulch, or rocks — never the lawn. This orientation stops the edging from being pushed sideways by grass roots and keeps the vertical face stable against the turf side.
How deep should the trench be for plastic landscape edging?
Standard residential plastic edging calls for a trench 4 inches deep, leaving roughly half an inch of the edging visible above grade. For heavy grass-control applications, dig 5 to 6 inches deep so the taller vertical wall blocks underground runners more effectively.
Can you install plastic edging without letting it warm up in the sun first?
Not recommended. Freshly uncoiled plastic edging resists straightening and tends to spring back into a coil. Warming it on pavement in direct sun for the manufacturer’s specified time makes it pliable enough to lay flat in the trench without fighting the curves.