Edging bricks add structure to your garden and help keep grass from growing where you don't want it. Although many people put edging bricks around flower beds, some gardeners also put the bricks around the base of their tree to keep mulch and pine straw in place, and make mowing under the tree easier. Edging with bricks isn't necessarily difficult, but it will take some time to get the edge looking just right.
Lay a garden hose or rope around the tree where you want the brick edging. This allows you to adjust the shape and width of the edging easily according to your preferences. Ensure that you install the edging far enough from the tree trunk that you won't hit any roots when you dig the trench for the bricks.
Remove any grass from around the base of the tree, all the way to the hose. Use an edger to cut the sod and make it easier to remove it. Be careful to not damage any shallow roots on the tree; some trees die if the roots get damaged.
Dig a flat-bottomed trench about one-third to one-half the depth of the brick, and slightly wider than the thickness of the bricks you will be using for the edging. Tamp down on the soil inside the trench with a 2- by 4-inch piece of wood.
Place the bricks laying lengthwise in the trench, so that the edge is flush with the grass, and flush with the end of the next brick. Ensure that the bricks are level by placing a level across two bricks. Add or remove soil as necessary under the bricks, or tamp down on the brick with a rubber mallet.
Add soil to the back of the bricks, and tamp down on each brick with a rubber mallet. Pack down the soil to help keep the bricks in place.
Add extra soil around the packed down bricks. This helps keep the bricks in place. Place mulch or pine straw around the inside of the edging to help keep the newly exposed soil moist.
If you want a more substantial looking brick edge, mix concrete according to the manufacturer's instructions, and apply another level or bricks in an offset a pattern.
Don't install the edging after a heavy rain. The ground may be too swollen and shift the shape of the brick edge.