Metal: A nearly invisible border
The simplest and most subtle borders that effectively separate your lawn from a garden are 4-in.deep strips of steel, aluminum or plastic. They all bend easily into smooth, graceful curves and stop the spread of grass roots. However, painted aluminum and steel offer the sleekest, most refined look because they almost disappear against the grass and garden bed. The plastic types have a prominent black bulge along the top edge. All work best on fairly even terrain; if you have a lot of dips and rises, it's easier to install a paver border.
Although aluminum and steel cost about the same, we chose aluminum because it was much lighter. It weighs about 41 lbs. per 100 ft., while steel weighs about 225. With aluminum, you get a professional look without the heavy lifting.
Plan to set the border with the top edge about 1/2 in. above the soil level to maintain the lawn/garden separation and keep roots from crossing over the top. This makes the border almost invisible and allows you to mow right over the top. However, be aware that the thin top edge can hurt bare feet. After cutting it, make sure you round off any sharp edges with a file.
Follow the photos for the basic installation techniques. The key to setting this border is to cut a clean vertical edge along the grass with a square spade (Photo 1). Then you can lay the border tightly against the edge when you stake and backfill it. There's no rule for shaping the edge. Simply follow the edges of your lawn, making smooth, gradual curves. To make smooth, sharp curves, bend the edging around a circular form.
Steel edging is the most common metal edging, although you might not find it at local nurseries. Look for it at larger garden centers or at landscape suppliers, which is where most pros get it. (Search “Landscape Equipment and Supplies” online or in your Yellow Pages.) Steel edging comes in 4-in. wide by 10-ft. long strips in a variety of colors. Keep in mind that it'll eventually rust, especially in a salt environment. It's heavy, floppy stuff and needs almost full support when you transport it.
Aluminum edging, besides being lighter and stiffer, won't rust and is also available in a wide variety of colors. Look for it through landscaping suppliers, although it might be difficult to find. You might have to order it. Be sure stakes are included with your purchase.
You'll find black plastic edging at every garden center and home center, sometimes in both regular and heavy-duty thicknesses. Buy the thicker material. It better withstands those inevitable bumps and hard knocks that go with lawn mowing.
Call your local utilities or 811 to locate underground lines before you dig and install all edging.
A paver border
Both concrete and brick pavers make a simple, handsome border and work well as edging material too. They're ideal when you want a wide border that keeps grass out of the garden, yet allows flowers and other plants to spill over without intruding onto the grass. You're less likely to chop them up with the lawn mower.
The paver design shown here also provides a nice, flat surface for the lawn mower wheel to roll along and make a clean cut. You shouldn't have to trim the edges after mowing. Concrete pavers (55¢ each) are designed for rugged outdoor use. Brick pavers ($1 each) are too, but don't confuse them with regular bricks, which are typically softer and more likely to break down. Set the pavers in a bed of sand for easier positioning and leveling (Photo 3).
The sand bed that you lay over landscape fabric keeps most grass types from sending roots under the edging and getting into the garden. Paver borders work well for straight, formal gardens but even better for informal yards with gradual curves and varying slopes. You can easily adjust them to follow the contours of an uneven yard. But they won't fit as well on tighter curves unless you alter the design and are willing to cut them to fit with a diamond blade saw.
Use a garden hose to mark the best-looking border shape and to make gradual curves (Photo 1). Don't hesitate to trim the trench a bit here or there as you cut the edge to smooth curves or alter the garden bed shape. For straight borders, follow a tightly stretched string line. Follow the photos for installing the pavers. It's important to set the front edge of the pavers about 1/2 in. above the soil in the lawn so the lawn mower can cut the grass cleanly. We also leveled our pavers from front to back to keep the row from dipping and rising, but it's not necessary and on slopes might look better if set on an angle. Just make sure the top of each paver sits flush with its neighbor and that the front edges create a smooth line. You can go back later and whack them perfectly flush with a block of wood and a hammer or a rubber mallet. The pavers we set on edge are primarily decorative, but they also raise the garden bed slightly and help retain mulch. Set them higher or lower to fit the needs of your garden.
A raised-bed border
A stone wall does more than make a clean border along your lawn. It's a handsome visual statement in itself, a great way to add depth and texture to a flat, featureless yard. It's practical, too.
If you have poor or clay soil, just fill the interior with topsoil and compost and you'll have a wonderful raised planting bed. It also provides good drainage, making it a great solution for low-lying, soggy gardens. And it's a good way to terrace a sloped yard and create nice, flat gardens.
To reduce maintenance we added a 4-in. deep trench that we lined with plastic edging and filled with mulch. The edging keeps grass roots from creeping into the stone wall, and the mulch provides a mowing track for the lawn mower wheels. With taller types of grass, you can mow right over the plastic border and cut the lawn edge cleanly. There's no need to trim the grass.
This project doesn't require any special skills, just a strong back. Besides a good shovel and a wheelbarrow, you'll need a cold chisel and a 2-lb.maul for breaking stones and driving edging stakes. Figure the cost at about $10 per foot of wall. Design your raised bed to blend into the contours of your yard like a natural feature. You can handle slopes in one of two ways. Either let your wall follow the slope of the yard for an informal look, or level the stones as we did and step the wall up or down as the slope requires to maintain approximately the same height.
The exact size of stacking stone for walls varies considerably by region. Visit a local landscape supplier to check types. (Ours is Chilton limestone.) For lawn edging, limit the height of your wall to two courses so you won't have stones falling out. Measure your wall length and make a sketch.
The stone dealer will help you figure out the quantities of all the materials you need. The stone will probably be sold by the ton or pallet and it's heavy. Have it delivered and dropped as close to the wall location as possible. And have gravel or sand delivered to use as a setting bed for the stone (Photo 2) as well as topsoil to fill behind the wall (Photo 5). The stone or landscaping dealer will help you calculate how much of these you need.
Follow the photos for step-by-step installation instructions. Get started by laying out the border with a garden hose or paint. We drew a curve by setting a string at a center point and marking an arc with paint (Photo 1). The trench width will vary depending on the width of the stone. Add 6 in. to the stone width (2 in. for the mowing edge plus 4 in. extra).
Generally it's best to keep the bottom row of stone an inch or so below the original soil level, but this will vary if you keep the stones level and the yard isn't level (what yard is?). At some point, you may have to step the stones up or down or use thinner or thicker stones. There's no rule here. Experiment when you lay the stones for the best appearance.
Lay the stones that have the most irregular faces in the first row so you can place the irregular face down in the gravel and level the top (Photo 3). Vary the sizes and colors for the best look. Chip off irregularities with the maul and chisel. Then add the second row (Photo 4). Make this row as stable as possible so the stones won't rock and fall off. As a last resort, stabilize the stones by shoving stone chips into the gaps.
Lay landscape fabric against the back of the wall before backfilling to keep dirt from washing out through the stone (Photo 5). Then install the plastic edging in front. Add organic mulch to finish up the mowing edge.