There are gardeners who can’t stand lawn edging. They feel a true gardener should be willing to redefine the border every 2 to 3 weeks with a lawn-edging tool. More power to them, but I prefer facility to repetitive labor.
And then, there are sophisticated gardeners who accept lawn edging as an unfortunate necessity, but only if it is made of metal. Plastic is simply too common. But metal is expensive, plastic isn’t. Call me plebeian, but I don’t mind the occasional sneer of a garden snob if I can save a considerable sum and still get good results, so I put in plastic edging.
My first plastic-edged beds are now over 20 years old and the inexpensive edging is still doing fine.
The Right Edging
Despite the claims of the various brands that theirs is stronger, more durable, etc., in fact, just about any plastic lawn edging will prove itself strong enough and durable enough, again as long as it is installed correctly.
The major factor to look for in lawn edging is the height. I’ve seen inexpensive lawn edging only 3 inches (7.5 cm) high, but grass rhizomes will simply go right underneath them and come up in your flower bed or vegetable garden: exactly what you were trying to prevent! 4-inch (10-cm) models are much more widely available… and also let grass through. Go for 5 inches (12 cm) at the very least. 6 inch (15 cm) lawn edging is harder to find, but worth it.
Typically lawn edging is sold in rolls of varying lengths, but there are also hammer-in types made of small segments that fit together and that you pound into the soil with a rubber mallet. It certainly seems easy enough, but I found them much harder to install than lawn edging sold in rolls: I kept hitting stones and rocks and then having to dig in to remove the obstacles. And though they were supposed to go in without any trenching, I ended punching a slot in the ground with my spade so I could insert them more readily. As a result of this experience, I would only recommend hammer-in types to someone with truly arable, stone-free soil, certainly not hard clay or rocky soil.
Installing Lawn Edging
It is easier to work with plastic edging on a relatively warm day: it is usually sold rolled up and will try to hold this form when it is cool. Leave it in the sun for an hour or two, though, and it will be more malleable, more readily adopting the shape you want to give it.
To install plastic edging between a lawn and a garden, inset a spade vertically all along the turf edge to a depth equal to the edge’s height, and push the earth forward, toward the garden, creating a trench with a vertical wall on one side and a wall with about a 45° angle on the other.
Place the edging in the trench, pressing it against the vertical wall. The top of the border should be about ½ inch (1.25 cm) above the ground: not so high that the lawnmower is likely to hit it, but still high enough to prevent turf grass rhizomes trying to climb over it.
The next step is the most crucial… and unfortunately less often applied. You have to secure the edging to the vertical trench wall, otherwise it would tend to work its way loose over time. This is doubly true in cold climates: if you’ve never heard the term “frost heave”, you’ll soon learn all about it if your edging is not staked into place.
Many models of edging have grooves or projections that are designed to stabilize them. One would think that the more pronounced these grooves or projections are, the more effective they would be, but from what I’ve seen any lawn edging that is not staked will eventually move, grooves or projections notwithstanding. I feel it is always worthwhile securing any edging with stakes.
Many lawn edging model kits do include anchoring stakes, but I find there are rarely enough of them. Rather than purchase additional stakes, a cheap and easy solution is just to buy 6-inch (15 cm) nails. They work as well as stakes and cost almost nothing.
Installing stakes or nails is a snap. Simply hammer them, horizontally or angled slightly downward, into the edging (which is pressed against the vertical trench wall, as mentioned above). Put in one about every foot (30 cm).
All that is left to do is to fill in the trench with soil and tamp it down. It’s that simple!
Joining Two Sections Together
For a smaller garden, one roll of lawn edging may be enough, but if not, you may have to find a way of joining two sections together.
The joint between two sections must be nearly seamless, otherwise turf grass rhizomes will work their way through the slightest gap to invade your flowerbed. Most lawn edges are sold with connectors designed to slip into or clip over (depending on the model) the top of the border. Unfortunately, this still leaves a section where the two edges are barely touching and that grass can easily breech. Here’s how to overcome that:
Cut off a 4-inch (10-cm) section of top bead (usually a tube) from one of the sections of edging. Use the connector to join the two sections, overlapping the two pieces of edging. This overlap will help prevent unwanted plants from crossing. To make the connection even more solid, punch an anchoring stake or nail through the two sections and into the trench wall.
And there you go! Properly installed, lawn edging will last 20 years or more. But you do have to install it correctly!