A brick raised bed should be approximately 45 cm (18 in) high, built using a single width of bricks. However, if you intend to sit on the edge of the raised bed, lay bricks of double thickness and finish with a bull-nosed coping. Use frost-proof bricks, leaving some of the joints above ground level open to act as weep holes. When the bed is completed, lay free-draining material such as hardcore in the base, followed by a water permeable membrane and finally the growing medium.

Concrete Footings

Before you start building, you must prepare a concrete footing at a depth that allows the first course of bricks to lie below ground level.

1. Mark out the site of the foundations with string lines stretched between wooden pegs; the footing should be at least 10 cm wider on each edge than the thickness of the brickwork.
2. Dig a trench around the perimeter of the wall of the required depth: a half-brick wall (the width of a single brick) will need to be 38 cm (15 in) deep, whilst a full-brick wall, (two bricks wide) will need to be 43 cm (17 in) deep. On heavy clay or in cold areas, you will need to increase the depth of the footing so that it is below the frost line.
3. Check that the base is level and the sides vertical.
4. Drive in pegs to the mark where the final level of concrete should be. Align with a spirit level and a length of wood spanning the pegs. The top of the footing should be at least 15 cm (6 in) below ground level to give adequate frost cover.
5. Soak the trench with water and allow it to drain. Then add 13cm (5in) of hardcore in the bottom and tamp it down.
6. Pour in 10 cm (4 in) of concrete (or 15 cm (6 in) for a full brick wall), slicing into the mix with a spade to work it in and dispel air bubbles.
7. Compact the concrete by tamping it down firmly with a length of timber, and ensure that it is level with the tops of the pegs. Leave the surface rough as a key for the mortar for the first course of bricks.
8. Allow the concrete to harden completely for a few days before laying the bricks or concrete blocks.

Rectangular Beds

A rectangular, brick bed is easy to construct; use a masonry mortar mix to lay the bricks, making sure that you form the corners using whole bricks at right angles. Stagger the brick joints on every level to create a sturdy wall.

Circular Beds

Position the bricks in a gentle curve so that there are no wide gaps on the outer edges of the bricks. Use the resulting shape to mark out the concrete footings. When the footings are ready, lay the bricks close to the inside of the footing edge, using wedges of mortar to fill the gaps on the outer face. Stagger the joints on every layer, then lay a final course of half bricks to create a smooth curve.

Take a look at our section on walls for more help and advice on building brick walls and working with brick in general.