Laying a brick island border around your garden can add a professional, finished look to your garden and keep the invasive grasses and weeds out. One of the key factors in laying a successful brick edging is to prepare the area properly before laying the brick border. Try to get landscaping bricks that are at least 4 inches high, so they can be efficient as a weed and grass barrier for your garden. You may need to select brick that will accommodate for the curves in your border, as well as some 90-degree corner stones. If you're creating a border around a larger garden, be sure to have an accessible "staging" area for the delivery of your materials. Select a spot to place the crushed rock, because it can kill any grass beneath it in less than 48 hours.
Determine the Amount of Materials You Need
Lay the string following the contours around the full perimeter of your garden, about 4 inches out from your plants. The string will signify where the centerline of the bricks will be.
Spray over the string with the marking spray paint to trace the center line of your border directly onto the ground. Keep in mind that you'll need to dig a trench that will extend 4 inches inside of the brick border and 4 inches outside of it.
Make a knot in your string where it meets at the starting point. Remove the string from the ground and lay it straight next to a measuring tape. Measure the string in feet.
Divide the string measurement by the length of the brick you will be using. The result will give you an accurate count on how many bricks you'll need to purchase for your garden island border. Multiply the result by the number of brick layers, if you're planning to have more than one layer of bricks.
Determine the amount of crushed rock you'll need for laying the base and filling the sides of the brick border. Measure the width of the brick you'll use for the border and add 8 inches to determine the width of your trench. Then, convert the sum to feet. For example, if you're using bricks that are 5 inches wide, you'd add the 8 inches, which would give you 13 inches (about 1.1 foot).
Multiply the trench width number by the string measurement. If your string measurement was 8 ½ feet, you'd multiply 1.1 foot by 8.5 feet to get 9.35.
Multiply the result by the depth of the trench in feet (4 inches = 1/3 of a foot or 0.33 feet) to get the amount of crushed rock you'll need in cubic feet. For example, if your result was 9.35, you'd multiply 9.35 by 0.33 to get about 3 cubic feet of crushed rock.
Multiply the string measurement by 0.66 feet (2/3 of a foot or 8 inches) to accommodate for the gap on either side of the brick border. Multiply the result by the height of the bricks in feet to get the amount of crushed rock you'll need to fill the sides of your brick border. If your brick height is 4 inches (1/3 of a foot), 8.5 feet string measurement x 0.66 foot x 0.33 foot brick height = 1.85 cubic feet.
Add the result from Step 7 to the result from Step 8 to get the total amount of crushed rock you'll need in cubic feet. For example, 3 cubic feet + 1.85 cubic feet = 4.85 total cubic feet. Always order 5 to 10 percent more crushed rock than you actually need to allow for errors in measurements (total cubic feet x 1.05 = total cubic feet plus 5 percent).
Prepare the Site to Install the Border
Remove all mulch close to the edges of where you're laying the border and ensure that the garden is weed and grass free. Make sure all perennials are about 1 foot back from the edge.
Define your border using wooden stakes. Remember that the width of your trench is the width of your bricks plus 8 inches. Place a row of stakes 4 inches plus half the width of the brick inside the spray-painted line and a row at the same distance on the outside of the line.
Tie strings to the stakes to establish the inner and outer border edges. For example, if your bricks are 4 inches wide, you'd place a row of stakes 6 inches (4 inches plus 2 inches) from the spray-painted line inside the border and 6 inches outside the line.
Make deep cuts following the strings on the inside and outside edges of the trench using a lawn edger. Remove the top 4 inches of sod using a spade. The trench floor should be flat and level.
Lay the Brick Border
Create a weed barrier in the trench by laying landscape fabric. Use some of the crushed rock to keep the landscape fabric in place. Line the bottom and sides of the trench completely.
Spread the crushed rock in the trench using a shovel and smooth out the rock using a rake. Work in layers, tamping down each layer with the small 2-by-6 board.
Lay one brick centered in the trench. The bricks should be about 1 inch higher than the grade to allow for the crushed rock to settle. Tamp the brick with the 2-by-6. Place another brick beside the first one and repeat the process.
Lay a 2-by-4 board down flat over the bricks periodically to make sure you have a flat surface. Fill in the outer and inner edges of the trench with crushed rock and tamp down.
Trim the excess landscape fabric from the edges of the trench. Sprinkle garden soil over the crushed rock. Level the soil with the ground grade on both sides of the trench. Use a fine spray from a hose to wash the bricks and settle the soil.