Dreamstime
The simplest of tricks often differentiates the appearance of a landscape installed by a professional and that installed by an amateur. One of those tricks is the way in which the edge of a planting bed or gravel bed is defined.
For a planting bed, amateurs might use no edging of any kind, allowing mulch to be the only visual separation between turf and bed, or maybe just dry stacked stone or rolled plastic edging. Sometimes an amateur will use steel edging, but all too often, it’s low-grade materials.
In contrast, professional landscapers tend to use deeply trenched grooves, termed infinity borders, commercial-grade steel edging, or cut and tumbled stone set in concrete. Of course, if a bricked-in border is required, since most landscape professionals do not have brick masonry skills, that work is sub-contracted or referred.
Just follow these simple steps, and you will create a stone border that looks it was installed by a professional.
But cut and tumbled stone, with irregular edges, is naturally forgiving and requires little skill to set in concrete for use as landscape edging. It seems to be the gold standard for professionally installed landscapes.
Here are the steps to achieve this look:
1. Select the stone.
There are several types to select from at local garden centers and stone yards. They have names like Arkansas Flagstone, Pennsylvania Bluestone, Tennessee Flagstone, Grey Stone, and Brown Stone. Additionally, the cuts and sizes vary, though I find the most ideal to be 4-inch cubes. The price varies among the types of stone, the volume of stone being purchased, and the degree of design assistance and delivery services needed. Generally, the price of the raw undelivered stone can vary anywhere from $5 to $20 per linear foot.
2. Gather the tools.
You’ll need a tool to mix the concrete, like a typical digging spade or hoe, and a wheelbarrow for mixing the concrete.
You’ll also need something to dig the trenches. I prefer a square-head “sharpshooter” shovel, about 4 inches wide, for straight edges, but many people prefer a trenching shovel, a device specially made for narrow and shallow trenches.
I also suggest either knee pads, a kneeling pad, or something else to kneel on. Though I rarely use one, it might be wise to wear a dust mask. Similarly, a mason’s trowel might come in handy.
Finally, a mallet with a non-marring head is an essential tool to avoid chipping the stone when tapping it into place. These are sometimes called rubber mallets or dead-blow hammers, both available at hardware stores.
3. Calculate the amount of concrete you need and purchase it.
I typically use the premixed products that just require adding water. At the time of this writing, the price for an 80-pound bag of concrete at both Home Depot and Lowe’s is $4.40. I use one 80-pound bag for every 6 or 7 feet of stone edging being installed.
4. Dig the trenches.
For 4-inch cubed stone, I like my garden trenches to be about 4-5 inches wide and at least 3 inches deep. The bigger the trenches, the more concrete you will need to fill them. Since this concrete edging will never have to bear much weight, I use what my experience tells me is the least amount necessary to firmly hold the stone in place for years to come.
Though I don’t think this is necessary, I have seen some people build forms of wood to hold the wet concrete, sometimes in lieu of digging trenches. One of my customers, Chris Peck, recently used this approach to great effect when following my advice to create a stone-bordered courtyard of #8 black crushed limestone gravel.
5. Mix the concrete and set the stone.
I like to mix just one bag of cement at a time so I can take a break whenever I like and not have to worry about the concrete hardening.
Before you mix the concrete, it’s best to line up all the stone you are going to use. Having them all lined up next to the trench, so that you can grab one and tap it in without getting off your knees, is ideal. This also helps you to be sure you have purchased enough.
Once the concrete is completely mixed, shovel it into the trench. Then use the mallet to tap the stones into place. For 4-inch cubes, I like to have at least 2 inches above the surface. I also like the top to be consistently level. Since even the highest grade of cut and tumbled cubes can vary in height, the amount of material below the surface may vary a bit for the top to be a consistent height. Similarly, since there may be a slight variation in width, I like to pick one side to be consistently flush across the stones, usually the side that is most easily seen. Thus, when creating a border between turf and planting beds, that is the turf side.
When I install the cut and tumbled stone, I make the border so that each stone is touching the stone next to it with as little space between the stones as possible. I have found mortaring between the stones to be counterproductive. It’s a lot of extra work with little visual improvement. Drainage is also important for most plants, and mortar between the stones inhibits drainage.
Just follow these simple steps, and you will create a stone border that looks it was installed by a professional.
John A. Jennings is an experienced garden designer, garden writer, and nursery manager. He also has degrees from both the University of Richmond and the University of Memphis.
