Before you start, make sure the ground is level. Use a shovel to dig out the area. Then, use the level to make sure it's flat. We're laying our bricks on compacted road base and don't need to lay a base or footings for the planter. But if you were building your planter box higher, and didn't have road base, you might need to lay a foundation and footings before laying the bricks.
We're making our planter box two bricks wide with a 10mm gap for the mortar, so it's 490mm wide and 1825mm long. Lay the two bricks that'll make up one side of the planter box, into place. Hammer in a peg next to them. Measure 490mm out from where the other side of the planter box is, then hammer in a peg. Run a string line between the pegs to mark where to lay the bricks.
You can use a wheelbarrow or a mixer to make the mortar. It's important to follow the instructions on the cement bag. Be careful not to add too much water. The ideal mortar mix should have a firm consistency. To check for the ideal consistency, hold the trowel upside down with mortar on it, a thin layer of the mortar should stay on the trowel.
Lay a bed of mortar on the ground, about 25mm thick. Embed the first brick into the mortar. Apply 10mm of mortar at one end of the second brick and place it next to the first. Check to see that the two bricks are level and straight. Wipe off any excess mortar as you go. Repeat this step for the other side. Then check that the two sides are level with each other. Adjust your string line, so that it's in line with the bricks.
Repeat the above steps to lay the first course. First, lay down a bed of mortar on the ground. Apply mortar to one end of the brick and lay it next to the side wall. Tap it down with the trowel so that it's the same height as the string line. Repeat this to lay the other bricks. It's important that the first course is level and straight. It'll make laying the other courses much easier.
We're laying our bricks in a half bond, which means the underlying brick is covered by a brick to the halfway mark. To cut the brick, measure and mark the halfway point. Use the hammer and bolster to cut the brick in half.
Once the brick is cut, continue to lay the bricks, starting with the half brick being laid closest to the wall. Follow the pattern of embedding the brick in mortar and butter each end. Make sure the bricks remain level and straight.
Quick tip to butter a brick: don't have too much mortar on the end of the trowel. Gently place the mortar on one side, then the other, and push it down so that it covers the full end surface of the brick.
Once the corners of the first course of bricks are in place, you can use purpose-built corner blocks to hold the string line in place. Continue laying until you have laid three courses of bricks.
While the mortar's still wet, use a damp sponge to wipe away any excess mortar and to smooth out the joints.
Once you've laid the brick planter box, finish the top off with a concrete cap. Use the same process to lay the cap that you used with the bricks. Apply mortar to the base and between each end of the cap. Use a rubber mallet to gently tap the capping stones into place. Leave the planter box to fully cure. This could take up to seven days.
You can leave the concrete cap natural or paint it. We painted ours so that it matches the colour scheme of the house.
If you're going to be filling the planter box with soil you will need to waterproof the bricks. Wait at least seven days for the mortar to dry before applying a bitumen based paint to the bricks.