Landscape edging for flower beds

When it comes to landscape edging, you may think: why bother? You’re not a person obsessed with order, you don’t need everything “just so,” you’ll let the plants grow where they want.

It won’t work, though. Nature needs boundaries, at least in our yards. With no edges, the mulch falls into the grass, the grass grows into the mulch, and the weeds do whatever they can to confuse things. You end up with weird intermediate zones that become endlessly irritating.

You can use a variety of materials to create clear edges but one of the most common (and cheapest) is black plastic edging. That’s what we chose for a new native flower garden that we put in our front yard. In preparation, I dug out all the sod and put in new topsoil.

(That was a huge dirt-moving operation; it probably would have been better to plan ahead, kill the grass, and use the existing soil. Anyway . . .)

I got this plastic edging at Menards. It was the “Pro” version, five inches high and a little thicker than the edging at the lower price points. So it was kind of the most expensive of the cheap edging. Of course there are more or less pricey kinds and people who say you need the priciest. I don’t have any opinion on that.

Basically, the steps are to dig a trench, fit the edging into the trench, and backfill the dirt around it. Let’s look a bit more closely.
The edging comes in a coil and is a little hard to uncoil at first. It’s easier to work with if you unroll it, set rocks on it to hold it down, and leave it in the sun for an hour or so. Be a little careful because it can get warm enough to scorch the grass underneath.

Meanwhile, dig the trench. I’d suggest using string tied between stakes to set out the boundaries where you want to dig. You can also mark an area using a special kind of spray paint — but the string is easier to move when you get it wrong.

I excavated the trench with this Fiskars flat-ended sod shovel, which bills itself as the “World’s Best Shovel.” I don’t know if that’s true but it is one of my favorite garden tools. The idea is to dig deep enough so that in the end the cylindrical part at the top of the landscape edging will be half covered by soil. Despite what you may see around the neighborhood, the edging is not supposed to stick up like a wall. Its barrier is largely below the surface, where it prevents runners from invading. And here’s another perk: if the edging is low, the lawnmower can go right over it. Easy!

To figure out the right depth, you can measure your shovel and make a chalk mark in the right place on the blade. Ideally, one side of the trench should be more or less vertical so the edging can stand up against it. The other side gets dug out at an angle.

Once I had the trench dug, I put in the edging. Some edging has a front and back but this was symmetrical so it could be installed either way. Then I had to do some adjustment: filling in or digging out so that the whole edging was approximately level. Once everything looked reasonably good, I followed some instructions from Renegade Gardener and “stomped the corners.” This means literally pushing down the inside corners with your shoe to compact the soil there and prevent the natural tendency of the edging to pull inward.

The edging needs one more step to keep it from moving out of place: stakes. These are especially important in the northern Midwest with its destructive annual freeze-thaw cycles. Some people recommend metal stakes; I used plastic and they seemed fine. The stakes need to be hammered right through the edging, maybe halfway down. Try to get them in at a 45-degree angle from vertical (though the Renegade Gardener site insists on a flatter angle, more parallel to the ground). The stakes should keep the edging in place more or less permanently.

I was making a flower bed in the shape of a giant oval so I also needed a connector to join the ends of the edging where they came together. The plastic can be cut with garden shears or whatever is at hand — the cutting isn’t pretty but that part will be mostly underground anyway. I drove a stake on each side of the seam for added stability.

The last step was to backfill the dirt that had been removed for the trench. Once the dirt was replaced, I walked the corners to tamp it down a little, sometimes adding more dirt if needed to fully refill the trench.

And that’s it! Once the plants get established, the edging becomes all but invisible, which is just what we want.

Links
Good basic overview of the installation steps
https://www.wikihow.com/Install-Plastic-Lawn-Edging

A more opinionated guide with some useful tricks (the image links are broken but the instructions are still valuable)
https://renegadegardener.com/care/how-to-install-plastic-landscape-edging-improperly/