Poly Landscape Edging
Poly edging is installed between planting beds and other landscape spaces, usually lawn, to separate the two spaces and keep turf from growing into the soil or mulched beds. Edging makes maintenance easier by reducing trimming along the bedlines.
Amounts, Specifications & Supplies:
- Poly edging comes in 20-foot strips. Commercial edging is 5-6" deep, and can be smooth or corrugated depending on the manufacturer. The amount needed can be determined from the landscape design or by measuring the length of the bedline. Three to four-inch deep edging is less expensive but is lightweight, flimsy, and difficult to install and does not last.
- A minimum of 4-5 stakes are needed for a 20' length of edging; curves will require 2-3 extra stakes. Often, stakes are supplied with the edging; however, more are always needed. Stakes should be a minimum of 6 inches long. Eight to ten-inch long 3/8" diameter timber spikes make excellent stakes.
- 1-inch galvanized sheetrock screws are needed for connecting edging sections.
- High quality edging is available from reputable nursery and garden centers.
Tools and Equipment:
- Flat-backed shovel for digging trench
- Sand shovel or spade for backfilling, etc.
- 1 lb hammer for driving stakes
- Spray paint, flags or a garden hose for marking bedlines to be edged
- An edging machine which does the trenching can be used for larger projects
Edging lines should be smooth and flowing. If the radius on curves is too tight, the edging will tend to lift out of the ground with the seasonal freeze and thaw cycle. Above-ground edging is often damaged during mowing.
When edging along lawn areas, the radius of curves should allow for easy use of riding lawn mowers.
1. Transfer the edging line from the design to the ground through a series of triangular measurements using a fixed feature at the site, such as a building, walk, driveway or curb. It is recommended this be done in combination with plant placement. Be sure adequate room is available for plants to reach their full mature spread.
2. Mark the proposed line using spray paint, flags, or garden hoses. Painting is the preferred method as it eliminates having flags or hose in the way during digging. Using the bottom of a strip of edging as a guide for painting works well and on curves helps make a smooth edging line.
3. Digging a trench in existing turf: Using a flat-backed garden spade, cut a vertical line into the turf along the edging line. Next, with your shovel at an angle, open a trench wide enough to leave room to install the edging and stakes. An edging machine could also be used to make the cut and prepare the trench. Dig deep enough to accommodate the depth of the edging being used with at least 1" to spare.
Place the edging along the flat vertical soil line so that the top of the edging ball is even with the soil surface. The ball cannot rest on the soil or as the ground heaves with the freeze-thaw cycle, the edging will be pushed out of the ground. The edging must be straight up and down or, with time, it will equalize causing an uneven edging line at the surface.
Drive 8-10" timber spikes through the edging into the undisturbed soil every 3-4'. This will help keep the edging from moving during and after installation. Backfill soil against the edging, taking care that the edging remains vertical. Tamp the soil firmly around the edging. If done correctly, the top of the edging will be flush with the soil on the turf side; there will be a slope leaving a 3-inch depth next to the edging and slanting 10-12" back into the bed for mulch on the bed side.
Digging a trench in disturbed soil: in new construction sites, there is no turf to support the vertical side of the trench. In this case, a trench is dug wide enough and deep enough to allow the edging to be installed to the proper depth. Two-foot segments of 3/8" re-rod can be used to support the edging in the proper location and elevation until the soil is returned to the trench. Water can be applied to help stabilize the loose soil next to the edging.
4. When connecting two strips of edging, cut a 2-3"section of the ball away using a sharp knife or old hand prunner, insert the connector tube provided with the edging, and overlap the flat part of the edging. Use 1" galvanized sheetrock screws to secure the two pieces of edging, or insert a stake through both pieces of edging into the undisturbed soil. Screws can also be used to hold the connector tube in place.
Poor connections will allow edging to pull apart.
5. When edging starts at sidewalks, buildings or other features, use a treated wooden stake to hold the end in place. A 1x3" stake 12" long can be driven into the soil holding the edging in line and at the proper elevation. Secure the edging to the stake with sheetrock screws. The edging should be below sidewalk level to prevent damage during snow removal.
This implementation report is based on landscape projects completed by University of Minnesota students enrolled in landscape design and implementation courses, Department of Horticultural Science.